Isolation and characterization of bone mesenchymal cell small extracellular vesicles using a novel mouse model.

Extracellular vesicles (EVs) are key mediators of cell-cell communication and are involved in transferring specific biomolecular cargo to recipient cells to regulate their physiological functions. A major challenge in the understanding of EV function in vivo is the difficulty ascertaining the origin of the EV particles. The recent development of the "Snorkel-tag", which includes EV-membrane-targeted CD81 fused to a series of extra-vesicular protein tags, can be used to mark EVs originating from a specific source for subsequent isolation and characterization. We developed an in vivo mouse model, termed "CAGS-Snorkel", which expresses the Snorkel-tag under the control of the Cre-lox system, and crossed this mouse with either Prx1-Cre (mesenchymal progenitors) or Ocn-Cre (osteoblasts/osteocytes) and isolated Snorkel-tagged EVs from the mouse bone marrow plasma using a magnetic bead affinity column. miRNA-sequencing was performed on the isolated EVs, and although similar profiles were observed, a few key miRNAs involved in bone metabolism (miR-106b-5p, miRs-19b-3p and miRs-219a-5p) were enriched in the Ocn-derived relative to the Prx1-derived EV subpopulations. To characterize the effects of these small EVs on a bone cell target, cultured mouse bone marrow stromal cells (mBMSCs) were treated with Prx1 or Ocn EVs, and mRNA-sequencing was performed. Pathways involved in ossification, bone development and extracellular matrix interactions were regulated by both EV subpopulations, whereas a few pathways including advanced glycation end-products (AGE) signaling, were uniquely regulated in the Ocn EV subpopulation, underlying important biological effects of specific EV subpopulations within the bone marrow microenvironment. These data demonstrate that EV isolation in vivo using the CAGS-Snorkel mouse model is a useful tool in characterizing the cargo and understanding the biology of tissue-specific EVs. Moreover, while bone mesenchymal cell populations share a common EV secretory profile, we uncover key differences based on the stage of osteoblastic differentiation that may have important biological consequences.

Extracellular vesicles (EVs) are small, lipid-based particles that are produced by all cells in the body, and function as a method of communication among different cells in a particular microenvironment. However, identification of the source of the EVs is difficult following export from the cell which the EV is produced. To facilitate the identification and characterization of the active molecules contained within EVs from a particular cell-type, we developed a new mouse model (CAGS-Snorkel) which allows for identification of the EV source cell using specific protein molecules on the EVs in only one particular cell- or tissue-type. As a proof-of-principle, we compared the microRNA EV cargo in cells from early bone cell progenitors and mature bone cells in the bone marrow microenvironment. We find that a number of microRNAs, molecules involved in the function and regulation of cellular processes, are expressed both in common and specifically within those two cell types. Notably, when purified EV subpopulations from these cell types were used to treat bone cell cultures, we find both common and unique gene expression and molecular pathway profiles. This work describes a new mouse model that will be useful in understanding how EVs function to carry important cellular information.

Cementless versus Cemented Total Knee Arthroplasty Using the Same Implant Design: A Mean 5-Year Follow-up Study.

Cementless implant use continues to increase primarily due to increased numbers of younger and obese patients opting for primary total knee arthroplasty (TKA). Given the increased use of cementless implants, the purpose of this study was to evaluate the midterm clinical performance of cementless TKA using a highly porous tibial baseplate compared with its cemented counterpart of the same system. We conducted a retrospective case-control study of 400 patients undergoing primary TKA that included 200 patients with cementless components matched for age and body mass index (BMI) to 200 patients with cemented implants of the same implant design with a 5-year follow-up. We evaluated clinical results, complications, revisions, and overall survivorship between the cohorts. Statistical analysis was performed using student t-test and chi-square analysis. There was no statistical difference in age (64.3 vs. 64.3 p = 0.81), BMI (34 vs. 33.1 p = 0.19), preoperative Knee Society Score (KSS) function (41 vs. 32.3 p = 0.22), and preoperative KSS knee score (39.2 vs. 38.3 p = 0.54) between the cementless and cemented cohorts, respectively. The cementless group had seven revisions, while the cemented group had nine revisions (p = 0.609). The cementless group had one revision due to aseptic loosening versus five in the cemented group (p = 0.09). Postoperative 5-year KSS knee scores were 92.84 versus 91.75 (p = 0.386) and function scores were 81.81 versus 69.65 (p = 0.00004) in the cementless and cemented groups, respectively. The cementless group had survivorship of 96.5% for all-cause revision compared with 95.5% in the cemented group at 5-year follow-up (p = 0.60). Cementless TKA using a highly porous tibial baseplate showed excellent midterm results with one case of aseptic loosening at 5-year follow-up and with similar Knee Society outcome scores and survivorship compared with the cemented group. Cementless TKA demonstrated noninferiority to cemented TKA and could be used as an alternative mode of fixation in patients opting for primary TKA. Additional long-term follow-up is needed to determine if cementless TKA can demonstrate improved survivorship over cemented TKA.

The glass transition and enthalpy recovery of polystyrene nanorods using Flash differential scanning calorimetry.

The glass transition (Tg) behavior and enthalpy recovery of polystyrene nanorods within an anodic aluminum oxide (AAO) template (supported nanorods) and after removal from AAO (unsupported nanorods) is studied using Flash differential scanning calorimetry. Tg is found to be depressed relative to the bulk by 20 ± 2 K for 20 nm-diameter unsupported polystyrene (PS) nanorods at the slowest cooling rate and by 9 ± 1 K for 55 nm-diameter rods. On the other hand, bulk-like behavior is observed in the case of unsupported 350 nm-diameter nanorods and for all supported rods in AAO. The size-dependent Tg behavior of the PS unsupported nanorods compares well with results for ultrathin films when scaled using the volume/surface ratio. Enthalpy recovery was also studied for the 20 and 350 nm unsupported nanorods with evolution toward equilibrium found to be linear with logarithmic time. The rate of enthalpy recovery for the 350 nm rods was similar to that for the bulk, whereas the rate of recovery was enhanced for the 20 nm rods for down-jump sizes larger than 17 K. A relaxation map summarizes the behavior of the nanorods relative to the bulk and relative to that for the 20 nm-thick ultrathin film. Interestingly, the fragility of the 20 nm-diameter nanorod and the 20 nm ultrathin film are identical within the error of measurements, and when plotted vs departure from Tg (i.e., T - Tg), the relaxation maps of the two samples are identical in spite of the fact that the Tg is depressed 8 K more in the nanorod sample.

Results of Primary Total Knee Arthroplasty in Patients on Chronic Psychotropic Medications.

BACKGROUND: Psychotropic medications are commonly used to treat several mental health conditions. The aim of this study was to determine the impact of psychotropic medications in patients undergoing primary total knee arthroplasty (TKA) with respect to postoperative opioid use, complications, patient-reported outcome measures, and satisfaction. METHODS: This is a retrospective cohort study of 514 consecutive patients undergoing primary TKA. There were 120 patients (23.3%) who were excluded due to preoperative opioid usage. The remaining 394 patients had a minimum 1-year follow-up. Of those, 133 (34%) were on psychotropic medications preoperatively and were compared to the remaining 261 (66%) patients who were not on psychotropics. Clinical data, satisfaction, Knee Society (KS) scores, Western Ontario McMaster Universities Arthritis Index, Patient-Reported Outcomes Measurement Index Score, Forgotten Joint Scores, Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, postoperative opioid medication usage, and complications were compared. RESULTS: The study cohort (psychotropic medications) had significantly lower postoperative KS Function, KS Knee, Forgotten Joint Scores, Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, Western Ontario McMaster Universities Arthritis Index, and Patient-Reported Outcomes Measurement Index Score compared to the control group. The study group had a lower overall satisfaction score (Likert scale 1 to 5) and a lower percentage of patients either satisfied or very satisfied (4.55 versus 4.79, P < .001; 92.0 versus 97.24%, P = .03, respectively). Postoperative opioid usage was significantly greater in the study group at both 6.4 weeks (range, 4 to 8) and 12-month follow-up (52.76 versus 13.33%, P < .001; 5.51 versus 0.39%, P = .002, respectively). There were no differences in complications and revisions between the groups. CONCLUSIONS: Patients on psychotropic medications should be educated on the risk of increased opioid consumption, diminished satisfaction, and patient-reported outcome measures following primary TKA. Given the large number of patients on psychotropic medications undergoing TKA, additional studies are needed to further improve clinical outcomes in this group.

Results of a Highly Porous Metal-Backed Cementless Patella Implant: A Minimum 5-Year Follow-Up.

Initial design cementless metal-backed patellar implants failed due to multiple reasons including implant design, use of first-generation polyethylene, and surgical technique. This study evaluates clinical outcomes and survivorship of total knee arthroplasty (TKA) using a current generation highly porous metal-backed patellar component. One-hundred twenty-five consecutive primary cementless TKAs with a compression molded highly porous metal-backed patella were reviewed. One-hundred three TKAs (82.4%) with 5-year clinical and radiographic follow-up were available for review. These were matched with 103 consecutive TKAs using a cemented patella of the same implant design. The cementless cohort had a mean age of 65.5 years, body mass index (BMI) of 33.0, and follow-up of 64.4 months. Indications for cementless TKA were based on multiple factors including age, BMI, and bone quality. There were no revisions for loosening or mechanical failure of the cementless patella compared with two cemented patellae revised for aseptic loosening. Eight patients required revisions in the cementless cohort: three for prosthetic joint infection (PJI), two for instability, one periprosthetic femur fracture, one for patella instability, and one for extensor mechanism rupture. Five patients required revisions in the cemented cohort: two for aseptic patellar loosening, one for aseptic femoral loosening, one for PJI, and one for instability. All-cause survivorship at 5 years was 92.2 and 95.1% for the cementless metal-backed implant and cemented implant cohorts, respectively. Use of a compression molded highly porous metal-backed patella component demonstrated excellent clinical and radiographic results at 5-year follow-up. Longer follow-up is required to evaluate the ability of highly porous cementless patella implants to provide durable long-term fixation.

Cementless metal-backed patellar components in primary total knee arthroplasty using an implant of modern design.

Aims: The use of cementless total knee arthroplasty (TKA) components has increased during the past decade. The initial design of cementless metal-backed patellar components had shown high failure rates due to many factors. The aim of this study was to evaluate the clinical results of a second-generation cementless, metal-backed patellar component of a modern design. Methods: This was a retrospective review of 707 primary TKAs in 590 patients from a single institution, using a cementless, metal-backed patellar component with a mean follow-up of 6.9 years (2 to 12). A total of 409 TKAs were performed in 338 females and 298 TKAs in 252 males. The mean age of the patients was 63 years (34 to 87) and their mean BMI was 34.3 kg/m2 (18.8 to 64.5). The patients were chosen to undergo a cementless procedure based on age and preoperative radiological and intraoperative bone quality. Outcome was assessed using the Knee Society knee and function scores and range of motion (ROM), complications, and revisions. Results: A total of 24 TKAs (3.4%) in 24 patients failed and required revision surgery, of which five were due to patellar complications (0.71%): one for aseptic patellar loosening (0.14%) and four for polyethylene dissociation (0.57%). A total of 19 revisions (2.7%) were undertaken in 19 patients for indications which did not relate to the patella: four for aseptic tibial loosening (0.57%), one for aseptic femoral loosening (0.14%), nine for periprosthetic infection (1.3%), one for popliteus impingement (0.14%), and four for instability (0.57%). Knee Society knee and function scores, and ROM, improved significantly when comparing pre- and postoperative values. Survival of the metal-backed patellar component for all-cause failure was 97.5% (95% confidence interval 94.9% to 100%) at 12 years. Conclusion: The second-generation cementless TKA design of metal-backed patellar components showed a 97.5% survival at 12 years, with polyethylene dissociation from the metal-backing being the most common cause of patellar failure. In view of the increased use of TKA, especially in younger, more active, or obese patients, these findings are encouraging at mean follow-up of seven years.

Is There a Difference in PROMs Between Morbidly Obese Patients and Nonobese Patients Following Primary Total Knee Arthroplasty?

Background: Patient satisfaction and patient-reported outcome measures (PROMs) are important for patients, surgeons, and payers in the current healthcare climate. Morbidly obese patients (body mass index [BMI] >40) have demonstrated higher incidence of complications after total knee arthroplasty (TKA) and can have difficulty obtaining access for their surgical care. The purpose of this study was to evaluate PROMs and patient satisfaction in morbidly obese patients undergoing primary TKA. Methods: A total of 75 patients with BMI >40 kg/m2 undergoing robotic-assisted TKA were retrospectively identified and matched 2:1 to a consecutive cohort of patients with BMI <35. The average BMI of the study cohort was 42.4 kg/m2 (39.5-51.3) compared to 28.6 kg/m2 (18.5-34.9) in the control group. Clinical outcomes, PROMs, and patient satisfaction were evaluated at a minimum 2-year follow-up. Results: The patients of the BMI >40 cohort were less likely to be discharged home (P = .0076), had less active flexion at 2 years (P = .0046), and had worse knee scores at 2 years (0.0497). Despite this, the percentage of patients who were satisfied or very satisfied after surgery was similar between the groups (87.5% vs 91.2%, P = .1943). Conclusions: Morbidly obese patients are less likely to be discharged directly to home and may have functional differences after primary TKA. However, morbidly obese patients have similar PROMs and are as satisfied as nonobese patients at 2 years. Morbidly obese patients with end-stage knee osteoarthritis should also be able to enjoy the benefits of primary TKA following medical and surgical optimization.

Neoplastic Progression of Barrett's Esophagus Among Organ Transplant Recipients: a Retrospective Cohort Study.

BACKGROUND: Several small studies reported high risk of progression to high-grade dysplasia (HGD) and esophageal adenocarcinoma (EAC) in Barrett's esophagus (BE) patients who undergo solid organ transplantation (SOT) and implied that this may be due to immunosuppressant use. However, the major shortcoming of these studies was the lack of a control population. Therefore, we aimed to determine the rates of neoplastic progression in BE patients who underwent SOT and compare to that in controls and identify the predictors of progression. METHODS: This was a retrospective cohort study of BE patients seen in Cleveland Clinic and affiliated hospitals between January 2000 and August 2022. Demographics, endoscopic and histological findings, history of SOT and fundoplication, immunosuppressant use, and follow-up were abstracted. RESULTS: The study population consisted of 3466 patients with BE, of which 115 had SOT (lung 35, liver 34, kidney 32, heart 14, and pancreas 2) and 704 patients on chronic immunosuppressants but no history of SOT. During a median follow-up of 5.1 years, there was no difference in the annual risk of progression between the three groups (SOT=0.61%, no SOT but on immunosuppressants= 0.82%, and no SOT/no immunosuppressants= 0.94%, p=0.72). On multivariate analysis, immunosuppressant use (odds ratio (OR) 1.38, 95% confidence interval (CI) 1.04-1.82, p=0.025) but not SOT (OR 0.39, 95%CI 0.15-1.01, p=0.053) was associated with neoplastic progression in BE patients. CONCLUSION: Immunosuppression is a risk factor for progression of BE to HGD/EAC. Therefore, close surveillance of BE patients on chronic immunosuppressants needs to be considered.

Clinical Outcomes and Complications for Achalasia Patients Admitted After Per-Oral Endoscopic Myotomy.

Background: Per-oral endoscopic myotomy (POEM) is a rapidly emerging minimally invasive procedure for management of achalasia. Same-day discharge after POEM is safe and feasible; however, some patients may need hospitalization. We aimed to identify characteristics and outcomes for achalasia patients requiring hospitalizations after POEM in the United States (US). Methods: The US National Inpatient Sample was utilized to identify all adult achalasia patients who were admitted after POEM from 2016 to 2019. Hospitalization characteristics and clinical outcomes were highlighted. Results: From 2016 to 2019, we found that 1,885 achalasia patients were admitted after POEM. There was an increase in the total number of hospitalizations after POEM from 380 in 2016 to 490 in 2019. The mean age increased from 54.2 years in 2016 to 59.3 years in 2019. Most POEM-related hospitalizations were for the 65 - 79 age group (31.8%), females (50.4%), and Whites (68.4%). A majority (56.2%) of the study population had a Charlson Comorbidity Index of 0. The Northeast hospital region had the highest number of POEM-related hospitalizations. Most of these patients (88.3%) were eventually discharged home. There was no inpatient mortality. The mean length of stay decreased from 4 days in 2016 to 3.2 days in 2019, while the mean total healthcare charge increased from $52,057 in 2016 to $65,109 in 2019. Esophageal perforation was the most common complication seen in 1.3% of patients. Conclusion: The number of achalasia patients needing hospitalization after POEM increased. There was no inpatient mortality conferring an excellent safety profile of this procedure.