Assessing Bioprinted Functionalized Grafts for Biological Tendon Augmentation In Vitro.

Tendinopathy, characterized by inflammatory and degenerative changes, presents challenges in sports and medicine. In addressing the limitations of conservative management, this study focuses on developing tendon grafts using extrusion bioprinting with platelet-rich plasma (PRP)-infused hydrogels loaded with tendon cells. The objective is to understand paracrine interactions initiated by bioprinted tendon grafts in either inflamed or non-inflamed host tissues. PRP was utilized to functionalize methacrylate gelatin (GelMA), incorporating tendon cells for graft bioprinting. Bioinformatic analyses of overexpressed proteins, predictive of functional enrichment, revealed insights into PRP graft behavior in both non-inflamed and inflamed environments. PRP grafts activated inflammatory pathways, including Interleukin 17 (IL-17), neuroinflammation, Interleukin 33 (IL-33), and chemokine signaling. Interleukin 1 beta (IL-1b) in the graft environment triggered p38 mitogen-activated protein kinase (MAPK) signaling, nuclear factor kappa light chain enhancer of activated B cells (NF-kB) canonical pathway, and Vascular Endothelial Growth Factor (VEGF) signaling. Biological enrichment attributed to PRP grafts included cell chemotaxis, collagen turnover, cell migration, and angiogenesis. Acellular PRP grafts differed from nude grafts in promoting vessel length, vessel area, and junction density. Angiogenesis in cellular grafts was enhanced with newly synthesized Interleukin 8 (IL-8) in cooperation with IL-1b. In conclusion, paracrine signaling from PRP grafts, mediated by chemokine activities, influences cell migration, inflammation, and angiogenic status in host tissues. Under inflammatory conditions, newly synthesized IL-8 regulates vascularization in collaboration with PRP.

Sonographic pathoanatomy of greater trochanteric pain syndrome.

AIMS: To identify and highlight pertinent US features that could serve as imaging biomarkers to describe different patient phenotypes, within Great Trochanteric Pain Syndrome (GTPS) clinical diagnosis. MATERIALS AND METHODS: Using ultrasound we evaluated eighty-eight clinically diagnosed patients with GTPS, for tendon matrix changes and calcium deposits in the gluteus medius (superoposterior and lateral aspects) and in the gluteus minimus. Peritrochanteric examination included fascia lata, trochanteric bursa, cortical irregularities and the presence of enthesophytes. The association of pathological changes with pain and functionality was evaluated using multivariate regression models. RESULTS: Out of the 88 patients, 86 examinations (97.7%) detected gluteus medius tendinopathy, and 54 patients (61.4%) had gluteus minimus tendinopathy in addition. Calcium deposits were present in 97.7% of patients, associated with tenderness (p = 0.009), and most often located in the gluteus medius rather than in the gluteus minimus (p = 0.014); calcifications were associated with tendon thickness (p = 0.042), hypoechogenicity (p = 0.005) and the presence of partial tears (p = 0.030). Bursa swelling occurred in 36 patients (40.9%); multivariate regression models predicted less pain in patients with bursa distension (p = 0.008) and dysfunction in patients with gluteal muscle atrophy (p = 0.001) and loss of fibrillar pattern in the gluteus medius (p = 0.002). CONCLUSION: GTPS involves both degenerative calcifying gluteal tendinopathy and alterations in the peritrochanteric space associated with physical function and pain. The severity of GTPS can be assessed using ultrasound imaging biomarkers.

Blood-derived biomaterials for tissue graft biofabrication by solvent-based extrusion bioprinting.

This article provides an overview of the different types of blood-derived biomaterials that can be used as solvent additives in the formulation of inks/bioinks for use in solvent extrusion printing/bioprinting. We discuss the properties of various blood sub-products obtained after blood fractionation in terms of their use in tailoring ink/bioink to produce functional constructs designed to improve tissue repair. Blood-derived additives include platelets and/or their secretome, including signaling proteins and microvesicles, which can drive cell migration, inflammation, angiogenesis, and synthesis of extracellular matrix proteins. The contribution of plasma to ink/bioink functionalization relies not only on growth factors, such as hepatocyte growth factor and insulin growth factors, but also on adhesive proteins, such as fibrinogen/fibrin, vitronectin, and fibronectin. We review the current developments and progress in solvent-based extrusion printing/bioprinting with inks/bioinks functionalized with different blood-derived products, leading toward the development of more advanced patient-specific 3D constructs in multiple medical fields, including but not limited to oral tissues and cartilage, bone, skin, liver, and neural tissues. This information will assist researchers in identifying the most suitable blood-derived product for their ink/bioink formulation based on the intended regenerative functionality of the target tissue.

Biological Targets of Multimolecular Therapies in Middle-Age Osteoarthritis.

Knee osteoarthritis (OA) is a common condition, prevalent in middle-agedness, associated with chronic pain and impaired quality of life. Two interrelated biological processes fuel early OA progression: inflammation and structural tissues catabolism. Procatabolic and proinflammatory mediators are interconnected and form part of a self-perpetuating loop. They leverage OA research complexity because of the impossibility to discern certain spatiotemporal tissues' changes from others. Both are shared targets of versatile regenerative multimolecular therapies. In particular, platelet-rich plasma can interfere with inflammation and inflammatory pain. The therapeutic approach is to alter the vicious inflammatory loop by modifying the molecular composition of the synovial fluid, thereby paracrine cellular cross talk. Intra-articular injections of platelet-rich plasma can provide key factors balancing proinflammatory and anti-inflammatory factors, targeting macrophage dysfunction and modulating immune mechanisms within the knee.

Wound-Microenvironment Engineering through Advanced-Dressing Bioprinting.

In patients with comorbidities, a large number of wounds become chronic, representing an overwhelming economic burden for healthcare systems. Engineering the microenvironment is a paramount trend to activate cells and burst-healing mechanisms. The extrusion bioprinting of advanced dressings was performed with novel composite bioinks made by blending adipose decellularized extracellular matrix with plasma and human dermal fibroblasts. Rheological and microstructural assessments of the composite hydrogels supported post-printing cell viability and proliferation over time. Embedded fibroblasts expressed steady concentrations of extracellular matrix proteins, including type 1, 3 and 4 collagens and fibronectin. ELISA assessments, multiplex protein arrays and ensuing bioinformatic analyses revealed paracrine activities corresponding to wound-healing activation through the modulation of inflammation and angiogenesis. The two modalities of advanced dressings, differing in platelet number, showed differences in the release of inflammatory and angiogenic cytokines, including interleukin 8 (IL-8), monocyte chemotactic protein 1 (MCP-1), vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF). The conditioned media stimulated human-dermal-cell proliferation over time. Our findings open the door to engineering the microenvironment as a strategy to enhance healing.

Unraveling the Signaling Secretome of Platelet-Rich Plasma: Towards a Better Understanding of Its Therapeutic Potential in Knee Osteoarthritis.

Platelets and their secretory products play an important role in determining the balance between tissue repair and tissue damage. To obtain novel insights into the molecular composition of platelet-rich plasma (PRP) and contextualize them in knee osteoarthritis (OA), two different plasma formulations, namely PRP and platelet-poor plasma (PPP), were prepared from six healthy donors following a biobank-automated protocol. Inter-donor differences were analyzed, and pools were created before performing multiplexing protein arrays. In addition, PRP and PPP were prepared from six patients following our in-house protocols. Supernatants from PRP and PPP were harvested one hour after calcium chloride activation. Multiplexing protein arrays were performed in parallel for all plasma formulations. Results were normalized to fold change in relation to PPP and examined using Ingenuity Pathway Analysis Software. Bioinformatic predictions showed that PRPs constitute a signaling system with interrelated networks of inflammatory and angiogenic proteins, including but not limited to interleukin-6 and -8 (IL-6, IL-8), insulin like growth factor 1 (IGF-1), transforming growth factor beta, (TGF-b), and vascular endothelial growth factor (VEGF) signaling, underlying biological actions. Predictions of canonical systems activated with PRP molecules include various inflammatory pathways, including high-mobility group box protein (HMGB1) and interleukin 17 (IL-17) signaling, neuroinflammation, and nuclear factor-kappa b (NF-κB) pathways. Eventually, according to these predictions and OA evolving knowledge, selected PRP formulations should be tailored to modulate different inflammatory phenotypes, i.e., meta-inflammation, inflame-aging or posttraumatic inflammatory osteoarthritis. However, further research to discriminate the peculiarities of autologous versus allogeneic formulations and their effects on the various OA inflammatory phenotypes is needed to foster PRPs.

Plasma-Based Bioinks for Extrusion Bioprinting of Advanced Dressings.

Extrusion bioprinting based on the development of novel bioinks offers the possibility of manufacturing clinically useful tools for wound management. In this study, we show the rheological properties and printability outcomes of two advanced dressings based on platelet-rich plasma (PRP) and platelet-poor plasma (PPP) blended with alginate and loaded with dermal fibroblasts. Measurements taken at 1 h, 4 days, and 18 days showed that both the PRP- and PPP-based dressings retain plasma and platelet proteins, which led to the upregulation of angiogenic and immunomodulatory proteins by embedded fibroblasts (e.g., an up to 69-fold increase in vascular endothelial growth factor (VEGF), an up to 188-fold increase in monocyte chemotactic protein 1 (MCP-1), and an up to 456-fold increase in hepatocyte growth factor (HGF) 18 days after printing). Conditioned media harvested from both PRP and PPP constructs stimulated the proliferation of human umbilical vein endothelial cells (HUVECs), whereas only those from PRP dressings stimulated HUVEC migration, which correlated with the VEGF/MCP-1 and VEGF/HGF ratios. Similarly, the advanced dressings increased the level of interleukin-8 and led to a four-fold change in the level of extracellular matrix protein 1. These findings suggest that careful selection of plasma formulations to fabricate wound dressings can enable regulation of the molecular composition of the microenvironment, as well as paracrine interactions, thereby improving the clinical potential of dressings and providing the possibility to tailor each composition to specific wound types and healing stages.

Moving toward targeting the right phenotype with the right platelet-rich plasma (PRP) formulation for knee osteoarthritis.

Intra-articular injections of platelet-rich plasma (PRP) and other novel blood-derived products developed specifically for osteoarthritis (OA) can provide pain relief and potential benefits in disease progression. Meta-analyses show the clinical superiority of PRP compared with other intra-articular injections, but results are modest and the effect sizes are small. PRP injections in knee OA are performed indiscriminately, but the clinical response varies enormously between patients because of an array of mixed OA phenotypes. Subgroup analyses are scarce; some studies stratify patients according to radiographic severity and found better results in early OA, without consensus for more advanced stages of the condition. Parallel identification of soluble and imaging biomarkers is essential to personalise and leverage PRP therapies. The inflammatory phenotype is most interesting from the PRP perspective because PRPs modulate inflammation by releasing a large pool of chemokines and cytokines, which interact with synovial fibroblasts and macrophages; in addition, they can modulate the innate immune response. No soluble biomarkers have been discovered that have implications for OA research and PRP interventions. Clinical examination of patients based on their inflammatory phenotype and imaging identification of pain sources and structural alterations could help discern who will respond to PRP. Synovial inflammation and bone marrow lesions are sources of pain, and intra-articular injections of PRP combined with subchondral bone injection can enhance clinical outcomes. Further refining ultrasound phenotypes may aid in personalising PRP therapies. Intra-articular delivery combined with injections in altered ligamentous structures, medial and coronal ligaments or premeniscal pes anserinus showed positive clinical outcomes. Although the evidence supporting these approaches are weak, they merit further consideration to refine PRP protocols and target the right OA phenotypes.

Mesenchymal stromal cell products for intra-articular knee injections for conservative management of osteoarthritis.

Sports injuries and secondary joint problems, mainly of the knee, are common, especially in sports associated with high impact activities and/or torsional loading. The consequences can be career ending in elite athletes and reduce exercise activities in recreational people. Various cell products can be injected intra-articularly. First, fresh cellular mixtures can be prepared and injected in the same day, such as stromal vascular fraction of adipose tissue (SVF) and bone marrow concentrates (BMCs). Second, autologous mesenchymal stromal cells (MSCs) can be isolated from BMCs or SVF and, after several weeks of laboratory expansion, several millions of MSCs can be obtained for intra-articular injection. Finally, allogeneic MSCs from the bone marrow, adipose tissue or perinatal tissues of selected donors constitute an 'off-the-shelf' experimental treatment for injection delivery in patients with osteoarthritis of the knee. The perceived efficacy of all these products is based on the hypothesis of a paracrine mechanism of action: when living cells are delivered within the joint, they establish a molecular cross-talk with immune cells and local cell phenotypes, thereby modulating inflammation with subsequent modifications in the catabolic/degenerative milieu. Current clinical research examines whether injection delivery of MSCs translates into actual clinical benefits. Overall, clinical studies lack the quality needed to answer major research questions, including clinical and structural efficacy, optimal cell dose, and number of injections and specific protocol for cell delivery. Poor experimental designs are exacerbated by the diversity of patient phenotypes that hinder comparisons between treatments. Further understanding of disease pathology is paramount to develop potent function assays and understand whether the host tissue, the cell product or both should be primed before MSCs are injected intra-articularly.

Overview of Current Advances in Extrusion Bioprinting for Skin Applications.

Bioprinting technologies, which have the ability to combine various human cell phenotypes, signaling proteins, extracellular matrix components, and other scaffold-like biomaterials, are currently being exploited for the fabrication of human skin in regenerative medicine. We performed a systematic review to appraise the latest advances in 3D bioprinting for skin applications, describing the main cell phenotypes, signaling proteins, and bioinks used in extrusion platforms. To understand the current limitations of this technology for skin bioprinting, we briefly address the relevant aspects of skin biology. This field is in the early stage of development, and reported research on extrusion bioprinting for skin applications has shown moderate progress. We have identified two major trends. First, the biomimetic approach uses cell-laden natural polymers, including fibrinogen, decellularized extracellular matrix, and collagen. Second, the material engineering line of research, which is focused on the optimization of printable biomaterials that expedite the manufacturing process, mainly involves chemically functionalized polymers and reinforcement strategies through molecular blending and postprinting interventions, i.e., ionic, covalent, or light entanglement, to enhance the mechanical properties of the construct and facilitate layer-by-layer deposition. Skin constructs manufactured using the biomimetic approach have reached a higher level of complexity in biological terms, including up to five different cell phenotypes and mirroring the epidermis, dermis and hypodermis. The confluence of the two perspectives, representing interdisciplinary inputs, is required for further advancement toward the future translation of extrusion bioprinting and to meet the urgent clinical demand for skin equivalents.

Freeze-Drying of Platelet-Rich Plasma: The Quest for Standardization.

The complex biology of platelets and their involvement in tissue repair and inflammation have inspired the development of platelet-rich plasma (PRP) therapies for a broad array of medical needs. However, clinical advances are hampered by the fact that PRP products, doses and treatment protocols are far from being standardized. Freeze-drying PRP (FD-PRP) preserves platelet function, cytokine concentration and functionality, and has been proposed as a consistent method for product standardization and fabrication of an off-the-shelf product with improved stability and readiness for future uses. Here, we present the current state of experimental and clinical FD-PRP research in the different medical areas in which PRP has potential to meet prevailing medical needs. A systematic search, according to PRISMA (Preferred Reported Items for Systematic Reviews and Meta-Analyses) guidelines, showed that research is mostly focused on wound healing, i.e., developing combination products for ulcer management. Injectable hydrogels are investigated for lumbar fusion and knee conditions. In dentistry, combination products permit slow kinetics of growth factor release and functionalized membranes for guided bone regeneration.

Wound Dressing Selection Is Critical to Enhance Platelet-Rich Fibrin Activities in Wound Care.

The use of platelet-rich fibrin (PRF) is investigated in ulcer management because it provides a healing milieu rich in growth factors and cytokines. Although crucial, the relevance of secondary dressings is under-researched and no data support the use of any particular dressing in preference to another. We assessed the properties of different dressing categories, including alginates, hydrocolloids, foams, hydrofibers, films, meshes and gauzes, in terms of affinity for PRF, releasate management (retention/extrusion) and the kinetics of cytokine release as well as the influence of each combination product, [PRF + dressing], on dermal cell behaviour, aiming to provide useful information for choosing the most adequate dressing for each particular patient. Active dressings including alginates, hydrofibers, foams and hydrocolloids blend with PRF, creating a diverse combination of products with different performances. Alginate and hydrofiber showed the highest affinity but moderate retention of releasate, without interfering with cell functions. Instead, the foam sequestered the releasate and hindered the release of growth factors, thereby compromising cell activities. Film and mesh presented very poor releasate retention and performed similarly to PRF by itself. Affinity index and releasate management explained 79% of platelet-derived growth factor (PDGF-BB) concentration variability, p < 0.001. Cell proliferation depended on the ability of the combination product to retain/release supernatant, PDGF-BB concentration and cell adhesion R2 = 0.91, p = 0.014.

Stromal vascular fraction technologies and clinical applications.

Introduction: The heterogeneous pool of cells found in the stromal vascular fraction of adipose tissue (SVF) and the purified mesenchymal stromal/stem cells (ASCs) isolated from this pool have increasingly been used as therapeutic tools in regenerative medicine.Areas covered: As SVF and ASCs are different, and should be used in different manners according to various clinical and biological indications, we reviewed the current literature, and focused on the clinical use of SVF to appraise the main medical fields for development. Both enzymatic digestion and mechanical disruption have been used to obtain SVF for non-homologous use. The safety and/or benefits of SVF have been examined in 71 clinical studies in various contexts, mainly musculoskeletal conditions, wound healing, urogenital, and cardiovascular and respiratory diseases. The use of SVF as a therapy remains experimental, with few clinical trials.Expert opinion: SVF provides a cellular and molecular microenvironment for regulation of ASC' activities under different clinical conditions. SVF may enhance angiogenesis and neovascularization in wound healing, urogenital and cardiovascular diseases. In joint conditions, therapeutic benefits may rely on paracrine immune-modulatory and anti-inflammatory mechanisms. Novel point of care methods are emerging to refine SVF in ways that meet the regulatory requirements for minimal manipulation.

Blood-Derived Products for Tissue Repair/Regeneration.

Medical interest in "blood-derived products for tissue repair/regeneration" has old roots, starting with chronic wounds in the 1980s, and boosted by sports medicine at the beginning of the millennium, when elite athletes treated with platelet rich plasma (PRP) resumed competition earlier than expected [...].

Platelet-rich plasma versus lidocaine as tenotomy adjuvants in people with elbow epicondylopathy: a randomized controlled trial.

OBJECTIVES: To determine the efficacy of platelet-rich plasma (PRP) compared to lidocaine as a tenotomy adjuvant for people with elbow tendinopathy. METHODS: Our study was a parallel-group, double-blind, randomized trial involving 71 patients with recalcitrant elbow tendinopathy who received two sessions of ultrasound-guided tenotomy with either PRP or lidocaine in a tertiary public hospital. The primary end point was the percentage of patients with an improvement exceeding 25% reduction in disability (Spanish version of the Disabilities of the Arm, Shoulder and Hand questionnaires-DASH-E) at 6 and 12 months; the secondary outcome was the percentage of patients exceeding 25% reduction in pain (VAS-P). RESULTS: There was no evidence of significant differences in the proportion of patients who experienced clinically relevant improvements. After 6 months, 18 patients (78.59%) in the lidocaine group and 19 patients (73.08%) in the PRP group showed improved function above 25% (unadjusted odds ratio, 0.90; 95% confidence interval [CI], 0.90 (0.17 to 4.60)); 21 patients (72.21%) in the lidocaine group versus 22 patients (84.62%) in the PRP group achieved more than 25% pain reduction (unadjusted odds ratio, 0.48; 95% CI, 0.10 to 2.37). After 12 months, 17 patients (70.83%) in the lidocaine group versus 19 patients (76%) in the PRP group had improved function (unadjusted odds ratio, 0.71; 95% CI, 0.13 to 3.84), and 19 patients (76%) in the lidocaine group versus 20 patients (90.91%) in the PRP group had improved pain above 25% (unadjusted odds ratio, 0.35; 95% CI, 0.06 to 2.51). Hypercholesterolemia and baseline vascularization influenced outcomes. There were no differences between groups in the adjusted odds ratios. CONCLUSION: PRP results in similar improvements to those obtained with lidocaine. Selecting patients according to their pretreatment status can improve treatment efficacy. TRIAL REGISTRATION: NCT01945528 , EudraCT 2013-000478-32. Registered 18 August 2013, enrolment of the first participant 10 March 2014.

Needle tenotomy with PRP versus lidocaine in epicondylopathy: clinical and ultrasonographic outcomes over twenty months.

OBJECTIVE: To investigate whether pathological changes in elbow epicondylopathy, as assessed by conventional ultrasonography and clinical outcomes, could be modified following tenotomy with platelet-rich plasma (PRP) versus tenotomy with lidocaine. METHODS: This prospective sub-study was part of a patient- and assessor-blinded, superiority-type, randomized, lidocaine-controlled trial that was performed in a tertiary hospital to assess the effectiveness of PRP versus lidocaine as tenotomy adjuvants in patients with epicondylopathy. Patients were followed after two sessions of tenotomy with either PRP or lidocaine adjuvants (4 ml) within a 2-week interval. Tendon thickness, echotexture, and neovascularization were assessed as secondary outcome measurements at baseline and at 3, 6, 12, and 20 months after treatment, and correlations with clinical outcomes were examined. RESULTS: Twenty months after treatment, tenotomy induced changes in tendon structure, thickness (± = 0.0006), vascularity (p < 0.0001), and echotexture (p < 0.0001). In Disabilities of the Arm, Shoulder and Hand (DASH-E) and pain (VAS-P) scores, 80.85% and 90.91% of patients showed a meaningful clinical improvement, respectively, without differences between PRP and lidocaine. There were significant differences in between-group changes in vascularity over time, p = 0.037 and p = 0.049 in the unadjusted and adjusted models, respectively. There was no relationship between pain or function and sonographic entities at the various time points. CONCLUSIONS: Two successive needle tenotomies induced structural changes in recalcitrant epicondylopathy, with PRP displaying more vascularization and increased thickness over time compared to lidocaine. PRP compared with lidocaine did not result in improved function or decreased pain over 20 months.

Predictors of Outcome Following Tenotomy in Patients with Recalcitrant Epicondylopathy.

BACKGROUND: Elbow tendinopathies are associated with tenderness, pain, and functional disability with ensuing socioeconomic costs. There is lack of consensus regarding the best treatment for patients recalcitrant to first-line conservative treatments. Percutaneous needle tenotomy is considered a regenerative approach that injures the tendon to elicit a healing response. OBJECTIVE: To investigate whether demographic characteristics, clinical factors, baseline sonographic entities, or their interactions are related to the likelihood of responding positively to needle tenotomy over a 1-year follow-up period. DESIGN: Prospective case series. SETTING: Tertiary institutional hospital. PARTICIPANTS: Patients with elbow tendinopathy for whom conservative treatments had failed and who had persistent symptoms lasting for at least 3 months. METHODS: Patients underwent needle tenotomy with or without PRP followed by a lighter needle tenotomy within a 2-week interval as part of treatment. MAIN OUTCOME MEASUREMENTS: Disabilities of the Arm, Shoulder and Hand (DASH) and Visual Analogue Scale for pain (VAS-P) scores were assessed before intervention (baseline) and at 6 weeks and 3, 6, and 12 months after intervention. A generalized linear mixed effects model was created to examine whether injectate type, clinical, demographic, or pretreatment sonographic entities or their interactions influenced clinical outcomes. RESULTS: The authors analyzed 74 elbows (71 patients). At baseline, analyzed patients (mean age: 49.48 years; 51.35% women) scored 43.30 and 5.83 on the DASH and VAS-P, respectively. Pretreatment tendon vascularization was a predictor of pain (P = .011) and DASH score changes (P = .019). The linear mixed effect model revealed that male gender and hypercholesterolemia were associated with enhanced functional recovery, (P = .020 and P < .001, respectively). Moreover, the interactions between pretreatment vascular status (P = .039), echotexture (P = .037) and enthesophytes (P = .028) influenced the temporal pattern of functional recovery after needle tenotomy. CONCLUSIONS: Baseline patient characteristics, such as gender and hypercholesterolemia, along with ultrasound features may be predictive of outcomes following needle tenotomy for elbow tendinopathy. LEVEL OF EVIDENCE: IV (NCT01945528).

New biotechnologies for musculoskeletal injuries.

The practice of any sport is inherently associated with the risk of musculoskeletal lesions. We describe regenerative medicine technologies, including cellular therapies, gene therapies and multimolecular preparations of growth factors and cytokines, which are expected to advance the field of orthopaedics and sports medicine. Gene therapy involves the introduction of genetic information in the injured tissue to help that tissue to heal and, possibly, regenerate. Cell therapies used in clinical practice are based on the transplantation of adult human cells, which can be at different stages of differentiation. Currently, the stromal vascular fraction, containing stem cells and other niche components, has been injected in the articular cartilage of the knee or delivered via arthroscopy. Bone marrow concentrate (BMC) has been used to manage focal chondral defects via arthroscopy with promising clinical results. In addition, purified mesenchymal stem cells (MSCs) have been injected or delivered as an adjuvant to arthroscopic microfractures, and patients have shown improved clinical outcomes. Laboratory-expanded MSCs injected in osteoarthritis moderately improved pain and functional outcomes. MSC treatment in the form of stromal vascular fraction (SVF) or BMC or laboratory expanded adhesive cells (bone marrow and adipose derived stem cells, BM-MSCs and ADSCs) has been proven to be safe. Despite their safety, expensive regulatory complexities required to implement cell-based therapies make these treatments unavailable for most patients. At present, although some results are promising, all biological interventions are experimental, and cost/efficacy has not been demonstrated yet. Moreover, short follow-up in most studies questions the durability of treatments.

Platelet-rich plasma for the treatment of diabetic foot ulcers: A meta-analysis.

Foot ulcer is a major complication of diabetes mellitus and often precedes leg amputation. Among the different methods to achieve ulcer healing, the use of platelet-rich plasma, which is rich in multiple growth factors and cytokines and may have similarities to the natural wound healing process, is gaining in popularity. A systematic review with meta-analyses was performed to evaluate the safety and clinical effectiveness of platelet-rich plasma for the treatment of diabetic foot ulcers compared to standard treatment or any other alternative therapy. The electronic databases Medline, EMBASE, CINAHL, and Cochrane Central Register of Controlled Trials were consulted in March 2017 with no restrictions placed on the publication date. Predefined criteria were used to determine inclusion of studies and to assess their methodologic quality. Eight randomized clinical trials and two prospective longitudinal-observational studies with control group were included. Platelet-rich plasma treatment increased the likelihood of chronic wound healing (RR = 1.32; 95% CI: 1.11, 1.57, I2 = 15%) while the volume of the ulcer (MD = 0.12 cm2 ; 95% CI: 0.08, 0.16; p < 0.01; I2 = 0%) and time to complete wound healing (MD = -11.18 days; 95% CI: -20.69, -1.68; I2 = 53%) decreased. Regarding safety profile, platelet-rich plasma did not differ from standard treatment in terms of probability of occurrence of wound complications (RR = 0.57; 95% CI: 0.25, 1.28; I2 = 0%) or recurrences (RR = 2.76; 95% CI: 0.23, 33.36; p = 0.43; I2 = 82%) but it decreased the rate of adverse events (RR = 0.80; 95% CI: 0.66, 0.96; p = 0.02; I2 = 0%). Cumulative meta-analysis revealed that there is enough evidence to demonstrate a statistically significant benefit. However, studies included presented serious methodologic flaws. According to the results, platelet-rich plasma could be considered a candidate treatment for nonhealing of diabetic foot ulcers.