Comparing MRI and arthroscopic appearances of common knee pathologies: A pictorial review.

Knee pathology, including anterior cruciate ligament (ACL) tears, meniscal tears, articular cartilage lesions, and intra-articular masses or cysts are common clinical entities treated by orthopedic surgeons with arthroscopic surgery. Preoperatively, magnetic resonance imaging (MRI) is now standard in confirming knee pathology, particularly detecting pathology less evident with history and physical examination alone. The radiologist's MRI interpretation becomes essential in evaluating intra-articular knee structures. Typically, the radiologist that interprets the MRI does not have the opportunity to view the same pathology arthroscopically. Thus, the purpose of this article is to illustratively reconcile what the orthopedic surgeon sees arthroscopically with what the radiologist sees on magnetic resonance imaging when viewing the same pathology. Correlating virtual and actual images can help better understand pathology, resulting in more accurate MRI interpretations. In this article, we present and review a series of MR and correlating arthroscopic images of ACL tears, meniscal tears, chondral lesions, and intra-articular masses and cysts. Short teaching points are included to highlight the importance of radiological signs and pathological MRI appearance with significant clinical and arthroscopic findings.

The Surgical Management of NCAA Division 1 College Football Injuries Post COVID-19: A Single Institution Retrospective Review.

ABSTRACT: Cohen, JL, Cade, WH, Harrah, TC, Costello II, JP, and Kaplan, LD. The surgical management of NCAA Division 1 college football injuries post COVID-19: A single institution retrospective review. J Strength Cond Res 38(5): 906-911, 2024-The unprecedented COVID-19 pandemic had a significant impact on college football operations, including athletes' training regimens. As a result of these changes, concern for increased injury susceptibility post COVID-19 regulations has become a point of discussion. The current study sought to evaluate the incidence of surgical injury among NCAA Division 1 college football players at the authors' institution during the first full season after start of the COVID-19 pandemic compared with previous years. Retrospective chart review was performed for all players who sustained injuries requiring surgery while a member of the NCAA Division 1 football program during the 2009-2021 seasons. A p -value of ≤0.05 was used to determine significance. A total of 23 surgical injuries occurred in 22 players during the 2021 season compared with 121 in 118 players in the 12 previous seasons combined ( p = 0.0178; RR = 1.47). There was a significant increase in shoulder injuries ( n = 13 vs. n = 31; p = <0.0001; RR = 3.05) and specifically a significant increase in labral tears ( n = 10 vs. n = 30; p = 0.0003; RR = 2.74). No difference was seen in knee injuries ( n = 10 vs. n = 77; p = 0.27; RR = 1.35) and specifically no difference in anterior cruciate ligament injuries ( n = 3 vs. n = 31; p = 0.77; RR = 1.17). This phenomenon is multifactorial in nature, but alterations to players' training and preparations because of the COVID-19 pandemic likely resulted in suboptimal conditioning, leading to the increased incidence of surgical injuries emphasizing the importance of adequate strength training and conditioning.

Acute Batter's Shoulder With Concomitant Superior Labrum from Anterior to Posterior Injury in a Collegiate Baseball Player.

An 18-year-old collegiate baseball player sustained an acute batter's shoulder injury causing a posterior shoulder dislocation with type IX 360° superior labrum from anterior to posterior tear. To the authors' knowledge, this description of batter's shoulder is not within the literature. The patient ultimately underwent arthroscopic labral repair and has fully returned to sport. In understanding the complexity of the shoulder during the batter's swing, this case demonstrates an expansion to the previously described pathophysiology of batter's shoulder.

Augmented Reality for Perioperative Anxiety in Patients Undergoing Surgery: A Randomized Clinical Trial.

Importance: Both augmented reality (AR) and virtual reality (VR) have had increasing applications in medicine, including medical training, psychology, physical medicine, rehabilitation, and surgical specialties, such as neurosurgery and orthopedic surgery. There are little data on AR's effect on patients' anxiety and experiences. Objective: To determine whether the use of an AR walkthrough effects patient perioperative anxiety. Design, Setting, and Participants: This randomized clinical trial was conducted at an outpatient surgery center in 2021 to 2022. All patients undergoing elective orthopedic surgery with the senior author were randomized to the treatment or control group. Analyses were conducted per protocol. Data analysis was performed in November 2022. Intervention: AR experience explaining to patients what to expect on their day of surgery and walking them through the surgery space. The control group received the standard educational packet. Main Outcomes and Measures: The main outcome was change in State-Trait Anxiety Inventory (STAI) from the screening survey to the preoperative survey. Results: A total of 140 patients were eligible, and 45 patients either declined or were excluded. Therefore, 95 patients (63 [66.3%] male; mean [SD] age, 38 [16] years) were recruited for the study and included in the final analysis; 46 patients received the AR intervention, and 49 patients received standard instructions. The AR group experienced a decrease in anxiety from the screening to preoperative survey (mean score change, -2.4 [95% CI, -4.6 to -0.3]), while the standard care group experienced an increase (mean score change, 2.6 [95% CI, 0.2 to 4.9]; P = .01). All patients postoperatively experienced a mean decrease in anxiety score compared with both the screening survey (mean change: AR, -5.4 [95% CI, -7.9 to -2.9]; standard care, -6.9 [95% CI, -11.5 to -2.2]; P = .32) and preoperative survey (mean change: AR, -8.0 [95% CI, -10.3 to -5.7]; standard care, -4.2 [95% CI, -8.6 to 0.2]; P = .19). Of 42 patients in the AR group who completed the postoperative follow-up survey, 30 (71.4%) agreed or strongly agreed that they enjoyed the experience, 29 (69.0%) agreed or strongly agreed that they would recommend the experience, and 28 (66.7%) agreed or strongly agreed that they would use the experience again. No differences were observed in postoperative pain levels or narcotic use. Conclusions and Relevance: In this randomized clinical trial, the use of AR decreased preoperative anxiety compared with traditional perioperative education and handouts, but there was no significant effect on postoperative anxiety, pain levels, or narcotic use. These findings suggest that AR may serve as an effective means of decreasing preoperative patient anxiety. Trial Registration: ClinicalTrials.gov Identifier: NCT04727697.

CD10-Bound Human Mesenchymal Stem/Stromal Cell-Derived Small Extracellular Vesicles Possess Immunomodulatory Cargo and Maintain Cartilage Homeostasis under Inflammatory Conditions.

The onset and progression of human inflammatory joint diseases are strongly associated with the activation of resident synovium/infrapatellar fat pad (IFP) pro-inflammatory and pain-transmitting signaling. We recently reported that intra-articularly injected IFP-derived mesenchymal stem/stromal cells (IFP-MSC) acquire a potent immunomodulatory phenotype and actively degrade substance P (SP) via neutral endopeptidase CD10 (neprilysin). Our hypothesis is that IFP-MSC robust immunomodulatory therapeutic effects are largely exerted via their CD10-bound small extracellular vesicles (IFP-MSC sEVs) by attenuating synoviocyte pro-inflammatory activation and articular cartilage degradation. Herein, IFP-MSC sEVs were isolated from CD10High- and CD10Low-expressing IFP-MSC cultures and their sEV miRNA cargo was assessed using multiplex methods. Functionally, we interrogated the effect of CD10High and CD10Low sEVs on stimulated by inflammatory/fibrotic cues synoviocyte monocultures and cocultures with IFP-MSC-derived chondropellets. Finally, CD10High sEVs were tested in vivo for their therapeutic capacity in an animal model of acute synovitis/fat pad fibrosis. Our results showed that CD10High and CD10Low sEVs possess distinct miRNA profiles. Reactome analysis of miRNAs highly present in sEVs showed their involvement in the regulation of six gene groups, particularly those involving the immune system. Stimulated synoviocytes exposed to IFP-MSC sEVs demonstrated significantly reduced proliferation and altered inflammation-related molecular profiles compared to control stimulated synoviocytes. Importantly, CD10High sEV treatment of stimulated chondropellets/synoviocyte cocultures indicated significant chondroprotective effects. Therapeutically, CD10High sEV treatment resulted in robust chondroprotective effects by retaining articular cartilage structure/composition and PRG4 (lubricin)-expressing cartilage cells in the animal model of acute synovitis/IFP fibrosis. Our study suggests that CD10High sEVs possess immunomodulatory miRNA attributes with strong chondroprotective/anabolic effects for articular cartilage in vivo. The results could serve as a foundation for sEV-based therapeutics for the resolution of detrimental aspects of immune-mediated inflammatory joint changes associated with conditions such as osteoarthritis (OA).

Therapeutic Perspectives for Inflammation and Senescence in Osteoarthritis Using Mesenchymal Stem Cells, Mesenchymal Stem Cell-Derived Extracellular Vesicles and Senolytic Agents.

Osteoarthritis (OA) is the most common cause of disability worldwide among the elderly. Alarmingly, the incidence of OA in individuals less than 40 years of age is rising, likely due to the increase in obesity and post-traumatic osteoarthritis (PTOA). In recent years, due to a better understanding of the underlying pathophysiology of OA, several potential therapeutic approaches targeting specific molecular pathways have been identified. In particular, the role of inflammation and the immune system has been increasingly recognized as important in a variety of musculoskeletal diseases, including OA. Similarly, higher levels of host cellular senescence, characterized by cessation of cell division and the secretion of a senescence-associated secretory phenotype (SASP) within the local tissue microenvironments, have also been linked to OA and its progression. New advances in the field, including stem cell therapies and senolytics, are emerging with the goal of slowing disease progression. Mesenchymal stem/stromal cells (MSCs) are a subset of multipotent adult stem cells that have demonstrated the potential to modulate unchecked inflammation, reverse fibrosis, attenuate pain, and potentially treat patients with OA. Numerous studies have demonstrated the potential of MSC extracellular vesicles (EVs) as cell-free treatments that comply with FDA regulations. EVs, including exosomes and microvesicles, are released by numerous cell types and are increasingly recognized as playing a critical role in cell-cell communication in age-related diseases, including OA. Treatment strategies for OA are being developed that target senescent cells and the paracrine and autocrine secretions of SASP. This article highlights the encouraging potential for MSC or MSC-derived products alone or in combination with senolytics to control patient symptoms and potentially mitigate the progression of OA. We will also explore the application of genomic principles to the study of OA and the potential for the discovery of OA phenotypes that can motivate more precise patient-driven treatments.

The roles and therapeutic potentialof mesenchymal stem/stromal cells and their extracellular vesicles in tendinopathies.

Tendinopathies encompass a highly prevalent, multi-faceted spectrum of disorders, characterized by activity-related pain, compromised function, and propensity for an extended absence from sport and the workplace. The pathophysiology of tendinopathy continues to evolve. For decades, it has been related primarily to repetitive overload trauma but more recently, the onset of tendinopathy has been attributed to the tissue's failed attempt to heal after subclinical inflammatory and immune challenges (failed healing model). Conventional tendinopathy management produces only short-term symptomatic relief and often results in incomplete repair or healing leading to compromised tendon function. For this reason, there has been increased effort to develop therapeutics to overcome the tissue's failed healing response by targeting the cellular metaplasia and pro-inflammatory extra-cellular environment. On this basis, stem cell-based therapies have been proposed as an alternative therapeutic approach designed to modify the course of the various tendon pathologies. Mesenchymal stem/stromal cells (MSCs) are multipotent stem cells often referred to as "medicinal signaling cells" due to their immunomodulatory and anti-inflammatory properties that can produce a pro-regenerative microenvironment in pathological tendons. However, the adoption of MSCs into clinical practice has been limited by FDA regulations and perceived risk of adverse events upon infusion in vivo. The introduction of cell-free approaches, such as the extracellular vesicles of MSCs, has encouraged new perspectives for the treatment of tendinopathies, showing promising short-term results. In this article, we review the most recent advances in MSC-based and MSC-derived therapies for tendinopathies. Preclinical and clinical studies are included with comment on future directions of this rapidly developing therapeutic modality, including the importance of understanding tissue loading and its relationship to any treatment regimen.

The Associations Between Quadriceps Tendon Graft Thickness and Isokinetic Performance.

BACKGROUND: Anterior cruciate ligament reconstruction (ACLR) using the quadriceps tendon is an increasingly popular technique. Both partial-thickness quadriceps tendon (PT-Q) and full-thickness quadriceps tendon (FT-Q) graft depths are employed. HYPOTHESIS/PURPOSE: This study was designed to assess isokinetic peak torque, average power, and total work during knee extension in patients with FT-Q or PT-Q grafts for ACLR. We hypothesized that both groups would show lower isokinetic values for the operated side, with greater deficits in the FT-Q group than in the PT-Q group. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 26 patients who underwent ACLR with either an FT-Q or PT-Q graft were recruited between June 2021 and November 2021. Patients underwent isokinetic knee extension testing at > 1 year after surgery. Mixed repeated-measures analysis of covariance with least square difference post hoc testing was used to determine significant differences or interactions for all variables. RESULTS: Peak torque was significantly lower for the operated limb than the nonoperated limb in the FT-Q group (mean difference [MD] ± standard error [SE], -38.6 ± 8.3 Ncm [95% CI, -55.7 to -21.5 Ncm]; P < .001; d = 0.90) but not in the PT-Q group (MD ± SE, -7.3 ± 7.7 Ncm [95% CI, -23.2 to 8.5 Ncm]; P = .348; d = 0.20). Similarly, average power for the operated limb was lower than that for the nonoperated limb in the FT-Q group (MD ± SE, -53.6 ± 13.4 W [95% CI, -81.3 to -26.9 W]; P < .001; d = 0.88) but not in the PT-Q group (MD ± SE, -4.1 ± 12.4 W [95% CI, -29.8 to 21.5 W]; P = .742; d = 0.07), and total work was lower for the operated limb compared with the nonoperated limb in the FT-Q group (MD ± SE, -118.2 ± 27.1 J [95% CI, -174.3 to -62.2 J]; P < .001; d = 0.96) but not in the PT-Q group (MD ± SE, -18.3 ± 25.1 J [95% CI, -70.2 to 33.6 J]; P = .472; d = 0.15). CONCLUSION: The FT-Q group showed significant deficits in the operated limb compared with the nonoperated limb for all isokinetic variables. In contrast, no significant differences were found between the nonoperated and operated limbs for the PT-Q group.

CD146+ Endometrial-Derived Mesenchymal Stem/Stromal Cell Subpopulation Possesses Exosomal Secretomes with Strong Immunomodulatory miRNA Attributes.

The perivascular localization of endometrial mesenchymal stem/stromal cells (eMSC) allows them to sense local and distant tissue damage, promoting tissue repair and healing. Our hypothesis is that eMSC therapeutic effects are largely exerted via their exosomal secretome (eMSC EXOs) by targeting the immune system and angiogenic modulation. For this purpose, EXOs isolated from Crude and CD146+ eMSC populations were compared for their miRNA therapeutic signatures and immunomodulatory functionality under inflammatory conditions. eMSC EXOs profiling revealed 121 in Crude and 88 in CD146+ miRNAs, with 82 commonly present in both populations. Reactome and KEGG analysis of miRNAs highly present in eMSC EXOs indicated their involvement among others in immune system regulation. From the commonly present miRNAs, four miRNAs (hsa-miR-320e, hsa-miR-182-3p, hsa-miR-378g, hsa-let-7e-5p) were more enriched in CD146+ eMSC EXOs. These miRNAs are involved in macrophage polarization, T cell activation, and regulation of inflammatory cytokine transcription (i.e., TNF-α, IL-1ß, and IL-6). Functionally, stimulated macrophages exposed to eMSC EXOs demonstrated a switch towards an alternate M2 status and reduced phagocytic capacity compared to stimulated alone. However, eMSC EXOs did not suppress stimulated human peripheral blood mononuclear cell proliferation, but significantly reduced secretion of 13 pro-inflammatory molecules compared to stimulated alone. In parallel, two anti-inflammatory proteins, IL-10 and IL-13, showed higher secretion, especially upon CD146+ eMSC EXO exposure. Our study suggests that eMSC, and even more, the CD146+ subpopulation, possess exosomal secretomes with strong immunomodulatory miRNA attributes. The resulting evidence could serve as a foundation for eMSC EXO-based therapeutics for the resolution of detrimental aspects of tissue inflammation.

Human infrapatellar fat pad mesenchymal stem cells show immunomodulatory exosomal signatures.

Within the human knee infrapatellar fat pad (IFP) and synovium, resident synoviocytes and macrophages contribute to the onset and progression of inflammatory joint diseases. Our hypothesis is that IFP-derived mesenchymal stem cells (IFP-MSC) robust immunomodulatory therapeutic effects are largely exerted via their exosomal (IFP-MSC EXOs) secretome by attenuating synoviocytes and macrophages pro-inflammatory activation. IFP-MSC EXOs showed distinct miRNA and protein immunomodulatory profiles. Reactome analysis of 24 miRNAs highly present in exosomes showed their involvement in the regulation of six gene groups, including immune system. Exosomes were enriched for immunomodulatory and reparative proteins that are involved in positive regulation of cell proliferation, response to stimulus, signal transduction, signal receptor activity, and protein phosphorylation. Stimulated synoviocytes or macrophages exposed to IFP-MSC EXOs demonstrated significantly reduced proliferation, altered inflammation-related molecular profiles, and reduced secretion of pro-inflammatory molecules compared to stimulated alone. In an acute synovial/IFP inflammation rat model, IFP-MSC EXOs therapeutic treatment resulted in robust macrophage polarization towards an anti-inflammatory therapeutic M2 phenotype within the synovium/IFP tissues. Based on these findings, we propose a viable cell-free alternative to MSC-based therapeutics as an alternative approach to treating synovitis and IFP fibrosis.

A Comparison of Two-Year Anterior Cruciate Ligament Reconstruction Clinical Outcomes Using All-Soft Tissue Quadriceps Tendon Autograft With Femoral/Tibial Cortical Suspensory Fixation Versus Tibial Interference Screw Fixation.

PURPOSE: To contribute to future quadriceps tendon harvest and fixation guidelines in the setting of anterior cruciate ligament reconstruction by comparing 2-year patient-reported subjective knee outcome scores and incidence of graft-related complications between the shorter harvest all-inside tibial-femoral suspensory fixation (TFSF) approach versus the longer harvest standard tibial interference screw fixation technique. METHODS: Patients who underwent primary anterior cruciate ligament reconstruction with all soft tissue quadriceps tendon autograft from January 2017 to May 2019 were identified for inclusion. Patients were matched into 2 cohorts of 62 based on reconstruction technique. All patients completed baseline and minimum 2-year International Knee Documentation Committee, Tegner Activity Level, and Lysholm questionnaires and were queried regarding subsequent procedures and complications to the operative knee. RESULTS: Average graft length for the all-inside TFSF was 69.55 (95% confidence interval 68.99-70.19) mm versus 79.27 (95% confidence interval 77.21-81.34) mm in the tibial screw fixation cohort (P = .00001). Two-year Lysholm scores were greater in the TFSF cohort (P = .04) but were not clinically significant. There was no difference in 2-year International Knee Documentation Committee (P = .09) or Tegner (P = .69) scores between cohorts, but more patients in the TFSF cohort returned to or exceeded their baseline activity level compared with the tibial screw fixation cohort (73% vs 61%, P = .25). Seven patients in the TFSF cohort versus 13 in the tibial screw fixation cohort reported anterior knee pain or kneeling difficulty (P = .22). There were no differences in reported complications. CONCLUSIONS: All-inside soft-tissue quadriceps tendon autograft with TFSF resulted in clinically comparable subjective outcome scores at 2 years to tibial screw fixation. There were also no differences in complications or reports of anterior knee pain or kneeling difficulty. All-inside TFSF can be a viable alternative to tibial screw fixation for all-soft tissue quadriceps autograft. LEVEL OF EVIDENCE: III, comparative therapeutic trial.

Distal Medial Collateral Ligament Grade III Injuries in Collegiate Football Players: Operative Management, Rehabilitation, and Return to Play.

CONTEXT: Management of isolated grade III medial collateral ligament injuries is controversial, as both nonoperative and operative management can result in return to play. However, operative management is recommended in elite athletes who have a grade III injury with distal avulsion. OBJECTIVE: We present a standardized rehabilitation protocol in a case series of 7 National Collegiate Athletic Association Division I American football athletes who sustained grade III distal medial collateral ligament tears that were repaired operatively, with emphasis on return to play. RESULTS: Median time to surgery was 4 days (range = 2-67 days). Median time from surgery to noncontact drills was 120.5 days (range = 104-168 days), and median time from surgery to full-contact sport was 181 days (range = 139-204 days). All athletes returned to play at their preinjury level of competition. CONCLUSIONS: Our study highlighted how operative management with a standardized rehabilitation protocol can be applied to Division I football players and result in safe return to play.

The 50 Most Cited Articles in Meniscal Injury Research.

BACKGROUND: Meniscal injuries are among the most common orthopaedic injuries, with a significant volume of published literature. PURPOSE: To perform a comprehensive bibliometric analysis that appropriately evaluates the 50 most cited articles in meniscal research. STUDY DESIGN: Cross-sectional study. METHODS: We performed a keyword search of the ISI Web of Knowledge database and then pared the results down to the 50 most cited articles using specific inclusion and exclusion criteria. Data extracted included title, first author, citation count, year of publication, topic, journal, article type, country of origin, and level of evidence. Correlation coefficients were calculated between publication date and citation density and between publication date and raw citation count. RESULTS: The 50 most cited articles were published from 1975 to 2013. The mean number of citations was 258.24 (range, 163-926; median, 225). The majority of articles were published in The American Journal of Sports Medicine (19%), the Journal of Bone and Joint Surgery (12%), and Arthritis & Rheumatology (14%). Most articles focused on either the anatomy and biomechanics of meniscal injury or on prevention and physical rehabilitation (12 papers each). CONCLUSION: The most popular fields of meniscal research involved anatomy/biomechanics and prevention/rehabilitation, and both are areas that will likely increase the probability of an article's being highly cited in the future. This study provided a quality selection of the most cited articles on meniscal injury and may provide a foundation for both beginner and senior clinician readers for further discussion and research.

Infrapatellar fat pad-derived mesenchymal stem cell-based spheroids enhance their therapeutic efficacy to reverse synovitis and fat pad fibrosis.

BACKGROUND: To investigate the in vitro and in vivo anti-inflammatory/anti-fibrotic capacity of IFP-MSC manufactured as 3D spheroids. Our hypothesis is that IFP-MSC do not require prior cell priming to acquire a robust immunomodulatory phenotype in vitro in order to efficiently reverse synovitis and IFP fibrosis, and secondarily delay articular cartilage damage in vivo. METHODS: Human IFP-MSC immunophenotype, tripotentiality, and transcriptional profiles were assessed in 3D settings. Multiplex secretomes were assessed in IFP-MSC spheroids [Crude (non-immunoselected), CD146+ or CD146- immunoselected cells] and compared with 2D cultures with and without prior inflammatory/fibrotic cell priming. Functionally, IFP-MSC spheroids were assessed for their immunopotency on human PBMC proliferation and their effect on stimulated synoviocytes with inflammation and fibrotic cues. The anti-inflammatory and anti-fibrotic spheroid properties were further evaluated in vivo in a rat model of acute synovitis/fat pad fibrosis. RESULTS: Spheroids enhanced IFP-MSC phenotypic, transcriptional, and secretory immunomodulatory profiles compared to 2D cultures. Further, CD146+ IFP-MSC spheroids showed enhanced secretory and transcriptional profiles; however, these attributes were not reflected in a superior capacity to suppress activated PBMC. This suggests that 3D culturing settings are sufficient to induce an enhanced immunomodulatory phenotype in both Crude and CD146-immunoselected IFP-MSC. Crude IFP-MSC spheroids modulated the molecular response of synoviocytes previously exposed to inflammatory cues. Therapeutically, IFP-MSC spheroids retained substance P degradation potential in vivo, while effectively inducing resolution of inflammation/fibrosis of the synovium and fat pad. Furthermore, their presence resulted in arrest of articular cartilage degradation in a rat model of progressive synovitis and fat pad fibrosis. CONCLUSIONS: 3D spheroids confer IFP-MSC a reproducible and enhanced immunomodulatory effect in vitro and in vivo, circumventing the requirement of non-compliant cell priming or selection before administration and thereby streamlining cell products manufacturing protocols.

Regulatory-compliant conditions during cell product manufacturing enhance in vitro immunomodulatory properties of infrapatellar fat pad-derived mesenchymal stem/stromal cells.

BACKGROUND AIMS: Mesenchymal stem/stromal cell (MSC)-based therapies have gained attention as potential alternatives for multiple musculoskeletal indications based on their trophic and immunomodulatory properties. The infrapatellar fat pad (IFP) serves as a reservoir of MSCs, which play crucial roles modulating inflammatory and fibrotic events at the IFP and its neighboring tissue, the synovium. In an effort to comply with the existing regulatory framework regarding cell-based product manufacturing, we interrogated the in vitro immunomodulatory capacity of human-derived IFP-MSCs processed under different conditions, including a regulatory-compliant protocol, in addition to their response to the inflammatory and fibrotic environments often present in joint disease. METHODS: Immunophenotype, telomere length, transcriptional and secretory immunomodulatory profiles and functional immunopotency assay were assessed in IFP-MSCs expanded in regular fetal bovine serum (FBS)-supplemented medium and side-by-side compared with same-donor cells processed with two media alternatives (i.e., regulatory-compliant pooled human platelet lysate [hPL] and a chemically reinforced/serum-reduced [Ch-R] formulation). Finally, to assess the effects of such formulations on the ability of the cells to respond to pro-inflammatory and pro-fibrotic conditions, all three groups were stimulated ex vivo (i.e., cell priming) with a cocktail containing TNFα, IFNγ and connective tissue growth factor (tumor-initiating cells) and compared with non-induced cohorts assessing the same outcomes. RESULTS: Non-induced and primed IFP-MSCs expanded in either hPL or Ch-R showed distinct morphology in vitro, similar telomere dynamics and distinct phenotypical and molecular profiles when compared with cohorts grown in FBS. Gene expression of IL-8, CD10 and granulocyte colony-stimulating factor was highly enriched in similarly processed IFP-MSCs. Cell surface markers related to the immunomodulatory capacity, including CD146 and CD10, were highly expressed, and secretion of immunomodulatory and pro-angiogenic factors was significantly enhanced with both hPL and Ch-R formulations. Upon priming, the immunomodulatory phenotype was enhanced, resulting in further increase in CD146 and CD10, significant CXCR4 presence and reduction in TLR3. Similarly, transcriptional and secretory profiles were enriched and more pronounced in IFP-MSCs expanded in either hPL or Ch-R, suggesting a synergistic effect between these formulations and inflammatory/fibrotic priming conditions. Collectively, increased indoleamine-2,3-dioxygenase activity and prostaglandin E2 secretion for hPL- and Ch-R-expanded IFP-MSCs were functionally reflected by their robust T-cell proliferation suppression capacity in vitro compared with IFP-MSCs expanded in FBS, even after priming. CONCLUSIONS: Compared with processing using an FBS-supplemented medium, processing IFP-MSCs with either hPL or Ch-R similarly enhances their immunomodulatory properties, which are further increased after exposure to an inflammatory/fibrotic priming environment. This evidence supports the adoption of regulatory-compliant practices during the manufacturing of a cell-based product based on IFP-MSCs and anticipates a further enhanced response once the cells face the pathological environment after intra-articular administration. Mechanistically, the resulting functionally enhanced cell-based product has potential utilization as a novel, minimally invasive cell therapy for joint disease through modulation of local immune and inflammatory events.

CD10/Neprilysin Enrichment in Infrapatellar Fat Pad-Derived Mesenchymal Stem Cells Under Regulatory-Compliant Conditions: Implications for Efficient Synovitis and Fat Pad Fibrosis Reversal.

BACKGROUND: Synovitis and infrapatellar fat pad (IFP) fibrosis participate in various conditions of the knee. Substance P (SP), a neurotransmitter secreted within those structures and historically associated with nociception, also modulates local neurogenic inflammatory and fibrotic responses. Exposure of IFP mesenchymal stem cells (IFP-MSCs) to a proinflammatory/profibrotic environment (ex vivo priming with TNFα, IFNγ, and CTGF) induces their expression of CD10/neprilysin, effectively degrading SP in vitro and in vivo. PURPOSE/HYPOTHESIS: The purpose was to test the therapeutic effects of IFP-MSCs processed under regulatory-compliant protocols, comparing them side-by-side with standard fetal bovine serum (FBS)-grown cells. The hypothesis was that when processed under such protocols, IFP-MSCs do not require ex vivo priming to acquire a CD10-rich phenotype efficiently degrading SP and reversing synovitis and IFP fibrosis. STUDY DESIGN: Controlled laboratory study. METHODS: Human IFP-MSCs were processed in FBS or either of 2 alternative conditions-regulatory-compliant pooled human platelet lysate (hPL) and chemically reinforced medium (Ch-R)-and then subjected to proinflammatory/profibrotic priming with TNFα, IFNγ, and CTGF. Cells were assessed for in vitro proliferation, stemness, immunophenotype, differentiation potential, transcriptional and secretory profiles, and SP degradation. Based on a rat model of acute synovitis and IFP fibrosis, the in vivo efficacy of cells degrading SP plus reversing structural signs of inflammation and fibrosis was assessed. RESULTS: When compared with FBS, IFP-MSCs processed with either hPL or Ch-R exhibited a CD10High phenotype and showed enhanced proliferation, differentiation, and immunomodulatory transcriptional and secretory profiles (amplified by priming). Both methods recapitulated and augmented the secretion of growth factors seen with FBS plus priming, with some differences between them. Functionally, in vitro SP degradation was more efficient in hPL and Ch-R, confirmed upon intra-articular injection in vivo where CD10-rich IFP-MSCs also dramatically reversed signs of synovitis and IFP fibrosis even without priming or at significantly lower cell doses. CONCLUSION: hPL and Ch-R formulations can effectively replace FBS plus priming to induce specific therapeutic attributes in IFP-MSCs. The resulting fine-tuned, regulatory-compliant, cell-based product has potential future utilization as a novel minimally invasive cell therapy for the treatment of synovitis and IFP fibrosis. CLINICAL RELEVANCE: The therapeutic enhancement of IFP-MSCs manufactured under regulatory-compliant conditions suggests that such a strategy could accelerate the time from preclinical to clinical phases. The therapeutic efficacy obtained at lower MSC numbers than currently needed and the avoidance of cell priming for efficient results could have a significant effect on the design of clinical protocols to potentially treat conditions involving synovitis and IFP fibrosis.

Infrapatellar fat pad-derived MSC response to inflammation and fibrosis induces an immunomodulatory phenotype involving CD10-mediated Substance P degradation.

The infrapatellar fat pad (IFP) serves as a reservoir of Mesenchymal Stem Cells (MSC), and with adjacent synovium plays key roles in joint disease including the production of Substance P (SP) affecting local inflammatory responses and transmitting nociceptive signals. Here, we interrogate human IFP-derived MSC (IFP-MSC) reaction to inflammatory and pro-fibrotic environments (cell priming by TNFα/IFNγ and TNFα/IFNγ/CTGF exposure respectively), compared with bone marrow-derived MSC (BM-MSC). Naïve IFP-MSC exhibit increased clonogenicity and chondrogenic potential compared with BM-MSC. Primed cells experienced dramatic phenotypic changes, including a sharp increase in CD10, upregulation of key immunomodulatory transcripts, and secreted growth factors/cytokines affecting key pathways (IL-10, TNF-α, MAPK, Ras and PI3K-Akt). Naïve, and more so primed MSC (both) induced SP degradation in vitro, reproduced with their supernatants and abrogated with thiorphan, a CD10 inhibitor. These findings were reproduced in vivo in a rat model of acute synovitis, where transiently engrafted human IFP-MSC induced local SP reduction. Functionally, primed IFP-MSC demonstrated sustained antagonism of activated human peripheral blood mononuclear cells (PBMC) proliferation, significantly outperforming a declining dose-dependent effect with naïve cohorts. Collectively, our in vitro and in vivo data supports cell priming as a way to enhance the immunoregulatory properties of IFP-MSC, which selectively engraft in areas of active synovitis/IFP fibrosis inducing SP degradation, resulting in a cell-based product alternative to BM-MSC to potentially treat degenerative/inflammatory joint diseases.

Comparison of Neuromuscular Firing Patterns of the Superficial Quadriceps in Soft Tissue Quadriceps Tendon Versus Bone-Patellar Tendon-Bone ACL Autografts.

BACKGROUND: Soft tissue quadriceps tendon (QT) autografts are increasingly popular as a primary graft choice for anterior cruciate ligament reconstruction (ACLR), but no study has compared superficial quadriceps activity levels and leg extension strength for QT versus bone-patellar tendon-bone (BTB) autografts. HYPOTHESIS: Harvesting the central portion of the QT will alter rectus femoris (RF) firing patterns during maximum voluntary isometric contraction. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 34 patients (age range, 18-40 years) who underwent ACLR using a BTB (n = 17) or QT (n = 17) autograft at a single institution participated in this study. Participants, who had no neuromuscular injury or prior surgery on either lower extremity, were at least 1 year after ACLR, and were cleared for full activity. Postoperative rehabilitation protocols were consistent across participants. Synchronized electromyography (EMG) and isometric torque data were collected from participants in the seated position with the hips flexed to 90° and the knee at 60° of flexion. Participants were asked to extend their knees as quickly as possible and perform maximum voluntary isometric contraction for 3 seconds. A practice trial and 3 test trials were completed with 30-second rest intervals. Mixed (2 graft × 2 limb) analyses of variance were used to examine differences in average and peak torque values and RF/vastus lateralis (VL) and RF/vastus medialis (VM) ratios. Lysholm and International Knee Documentation Committee (IKDC) scores were compared between groups using unpaired t tests. RESULTS: Significantly lower values were seen for the operative compared with the nonoperative extremity for average (P = .008; η2 = 0.201) and peak torque (P < .0001; η2 = 0.321), with no significant difference between graft types. Additionally, no significant differences in RF/VL or RF/VM ratios between limbs or graft types were observed. CONCLUSION: At 1 year after ACLR, QT and BTB autografts showed similar isometric strength deficits, with no differences in quadriceps muscle EMG ratios seen between the 2 graft types. The results support the use of a QT autograft for ACLR, as its graft harvest does not adversely affect quadriceps firing patterns in comparison with BTB graft harvest.

Patient-Reported Knee Outcome Scores With Soft Tissue Quadriceps Tendon Autograft Are Similar to Bone-Patellar Tendon-Bone Autograft at Minimum 2-Year Follow-up: A Retrospective Single-Center Cohort Study in Primary Anterior Cruciate Ligament Reconstruction Surgery.

BACKGROUND: Quadriceps tendon (QT)-bone autografts used during anterior cruciate ligament (ACL) reconstruction have provided comparable outcomes and decreased donor-site morbidity when compared with bone-patellar tendon-bone (BPTB) autografts. No study has directly compared the outcomes of the all-soft tissue QT autograft with that of the BPTB autograft. HYPOTHESIS: Patient-reported knee outcome scores and rates of postoperative complication after primary ACL reconstruction with QT autografts are no different from BPTB autografts at a minimum 2-year follow-up. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 75 patients who underwent primary autograft ACL reconstruction with QT or BPTB autografts between January 1, 2015, and March 31, 2016, at a single hospital center were contacted by telephone and asked to complete the International Knee Documentation Committee (IKDC) Subjective Knee Evaluation, Tegner activity level scale, and Lysholm knee scoring scale. Information about the subsequent surgeries performed on the operative knee was also collected. Statistical analysis was performed using the Kruskal-Wallis test and the Fisher exact test for categorical data. RESULTS: Fifty patients (28 QT, 22 BPTB) completed the surveys at a mean follow-up of 33.04 months (range, 24-44 months). For the QT versus the BPTB group respectively, the median IKDC scores were 94.83 (interquartile range [IQR], 7.61) versus 94.83 (IQR, 10.92) (P = .47), the median Tegner scores were 6 (IQR, 2.5) versus 6 (IQR, 2.75) (P = .48), and the median Lysholm scores were 95 (IQR, 9) versus 95 (IQR, 13) (P = .27). Additionally, 2 QT patients and 3 BPTB patients required follow-up arthroscopy for arthrolysis (P = .64). There was 1 graft failure in the QT group requiring revision surgery. CONCLUSION: There was no statistical difference in patient-reported knee outcomes or graft complication rates between the QT and BPTB autograft groups at a minimum 2-year follow-up after primary ACL reconstruction. This study highlights that the all-soft tissue QT autograft may be a suitable graft choice for primary ACL reconstruction.

Transcriptomic analysis of synovial extracellular RNA following knee trauma: A pilot study.

Traumatic knee injuries often result in damage to articular cartilage and other joint structures. Such trauma is a strong risk factor for the future development and progression of osteoarthritis (OA). The molecular mechanisms and signaling pathways modulating response to knee joint trauma remain unclear. Moreover, investigations of biomarkers influencing responses have been targeted rather than broad, unbiased discovery studies. Herein, we characterize the complete complement of extracellular RNA (exRNA) in the synovial fluid of 14 subjects following knee injury. Fluid was collected during surgery from the injured knees, and from the contralateral knee in a subset, undergoing surgical repair of the ACL and/or meniscal repair/debridement. Arthroscopic grading of chondral damage in four knee compartments was performed using the Outerbridge classification. exRNA was extracted and subjected to massively parallel total RNA sequencing. Differential abundance of RNA was calculated between the subject cohorts of injured and non-injured knee, average Outerbridge score ≥0.5 and less, and chronic and acute injury duration defined as ≤4 months till surgery or longer. Overall, expression of several thousand genes was identified in the synovial fluid. Furthermore, differential expression analysis suggests a role of exRNA fragments of matrix metalloproteinases and skeletal muscle fiber genes in the response to traumatic injury. Together, these data suggest that high-throughput approaches can indicate exRNA molecular signatures following knee trauma. Future studies are required to more fully characterize the biological roles of these exRNA and the cadence of their respective release that may lead to translational treatment options for post-traumatic OA. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1659-1665, 2018.