Comparison of Fusion Rates/Complications Between Different Types of Thumb Metacarpophalangeal Fusion Techniques

BACKGROUND

Thumb metacarpophalangeal (MP) fusion is generally successful; however, complications have been reported to occur in 0% to 30% of cases, whereas nonunion rates vary by method but, overall, are reported to occur in 0% to 15% of cases. Many fixation techniques have been described, but there is no consensus on the optimal fusion technique. Our goal was to compare complication and union rates of different thumb MP arthrodesis techniques.

METHODS

We performed a retrospective review of patients who underwent primary thumb MP fusion between 2000 and 2022. Patients who underwent revision fusion, fusion for infection, or amputation were excluded. Fusions of MP joints of other fingers were also excluded. Data collection consisted of demographic data, complications, time to fusion, rate of delayed union and rate of nonunion. Five different fusion constructs were evaluated during our study period: staples, Kirschner wires (K-wires), cerclage, K-wires with cerclage, and intramedullary screw.

RESULTS

Forty-seven patients underwent fusion with staples, 16 with K-wires, 14 with cerclage, 9 with K-wires and cerclage, and 6 with an intramedullary screw. The individual complication and nonunion rates differed significantly among the groups with the intramedullary screw group having a statistically higher rate of nonunion (P = .004). Furthermore, smoking, diabetes, and being overweight were associated with nonunions.

CONCLUSION

Union rates were significantly lower in patients treated with an intramedullary screw and those who are smokers, diabetics, and/or overweight. Caution should be exercised when using intramedullary screw fixation for MP fusion, especially in patients with these comorbidities.

Pseudoparesis and pseudoparalysis in the setting of massive irreparable rotator cuff tear: demographic, anatomic, and radiographic risk factors

BACKGROUND

The primary purpose of this study was to identify demographic, anatomic, and radiographic risk factors for active forward elevation (AFE) <90° in the setting of massive, irreparable rotator cuff tear (miRCT). The secondary purpose was to identify characteristics differentiating between patients with pseudoparalysis (AFE <45°) and pseudoparesis (AFE >45° but <90°).

METHODS

This was a retrospective case-control study reviewing patients with miRCTs at a single institution between January 12, 2016 and November 26, 2020. Patients were separated into 2 cohorts based on presence or absence of preoperative AFE <90° with maintained passive range of motion. Demographics, RCT pattern, and radiographic parameters were assessed as risk factors for AFE <90°. A secondary analysis was conducted to compare patients with pseudoparalysis and pseudoparesis.

RESULTS

There were 79 patients in the AFE <90° cohort and 50 patients in the control cohort. Univariate analysis confirmed significant differences between the AFE <90° and control cohort in age (71.9 ± 11.0 vs. 65.9 ± 9.1 years), arthritis severity (34.2% vs. 16.0% grade 3 Samilson-Prieto), acromiohumeral distance (AHD; 4.8 ± 2.7 vs. 7.6 ± 2.6 mm), fatty infiltration of the supraspinatus (3.3 ± 0.9 vs. 2.8 ± 0.8) and subscapularis (2.0 ± 1.2 vs. 1.5 ± 1.0), and proportion of subscapularis tears (55.7% vs. 34.0%). On multivariate analysis, age (odds ratio [OR] 1.08, P = .014), decreased AHD (OR 0.67, P < .001), severe arthritis (OR 2.84, P = .041), and subscapularis tear (OR 6.29, P = .015) were independent factors predictive of AFE <90°. Secondary analysis revealed tobacco use (OR 3.54, P = .026) and grade 4 fatty infiltration of the supraspinatus (OR 2.22, P = .015) and subscapularis (OR 3.12, P = .042) as significant predictors for pseudoparalysis compared to pseudoparesis.

CONCLUSIONS

In patients with miRCT, increased age, decreased AHD, severe arthritis, and subscapularis tear are associated with AFE <90°. Furthermore, patients with AFE <90° tend to have greater supraspinatus and subscapularis fatty infiltration. Lastly, among patients with AFE <90°, tobacco use and grade 4 fatty infiltration of the supraspinatus and subscapularis are associated with pseudoparalysis compared with pseudoparesis.

Grade 2, 3 and Dedifferentiated Chondrosarcomas: A Comparative Study of Isocitrate Dehydrogenase-Mutant and Wild-Type Tumors with Implications for Prognosis and Therapy

BACKGROUND

Grade 2 and 3 and dedifferentiated chondrosarcomas (CS) are frequently associated with isocitrate dehydrogenase (IDH) mutations and often exhibit a poor clinical outcome. Treatment is limited mainly to surgery. Defining IDH status (wild type (WT) and mutant) and the associated transcriptome may prove useful in determining other therapeutic options in these neoplasms.

METHODS

Formalin-fixed paraffin-embedded material from 69 primary and recurrent grade 2, 3 and dedifferentiated CS was obtained. DNA sequencing for IDH1 and IDH2 mutations (n = 47) and RNA sequencing via Nextseq 2000 (n = 14) were performed. Differentially expressed genes (DEGs) were identified and used to predict aberrant biological pathways with Ingenuity Pathway Analysis (IPA) software (Qiagen). Gene Set Enrichment Analyses (GSEA) using subsets C3, C5 and C7 were performed. Differentially expressed genes were validated by immunohistochemistry. Outcome analysis was performed using the Wilcoxon test.

RESULTS

A set of 69 CS (28 females, 41 males), average age 65, distributed among femur, pelvis, humerus, and chest wall were identified from available clinical material. After further selection based on available IDH status, we evaluated 15 IDH WT and 32 IDH mutant tumors as part of this dataset. Out of 15 IDH WT tumors, 7 involved the chest wall/scapula, while 1 of 32 mutants arose in the scapula. There were far more genes overexpressed in IDH WT tumors compared to IDH mutant tumors. Furthermore, IDH WT and IDH mutant tumors were transcriptomically distinct in the IPA and GSEA, with IDH mutant tumors showing increased activity in methylation pathways and endochondral ossification, while IDH WT tumors showed more activity in normal matrix development pathways. Validation immunohistochemistry demonstrated expression of WT1 and AR in IDH WT tumors, but not in IDH mutants. SATB2 was expressed in IDH mutant tumors and not in WT tumors. Outcome analysis revealed differences in overall survival between mutant and WT tumors (p = 0.04), dedifferentiated mutant and higher-grade (2, 3) mutant tumors (p = 0.03), and dedifferentiated mutant and higher-grade (2, 3) WT tumors (p = 0.03). The longest survival times were observed in patients with higher-grade WT tumors, while patients with dedifferentiated mutant tumors showed the lowest survival. Generally, patients with IDH WT tumors displayed longer survival in both the higher-grade and dedifferentiated groups.

CONCLUSIONS

Grade 2, 3 and dedifferentiated chondrosarcomas are further characterized by IDH status, which in turn informs transcriptomic phenotype and overall survival. The transcriptome is distinct depending on IDH status, and implies different treatment targets.

Criteria-based return to sport testing after open Latarjet reveals residual deficits and can be utilized for sports clearance with excellent outcomes at mean 3.6 year follow-up: A small case series of competitive athletes

OBJECTIVE

The purpose of this study was to assess the use of a criteria-based return to sport (CBRTS) test to evaluate readiness for return to play (RTP) in competitive athletes that underwent open Latarjet.

DESIGN

Retrospective case series.

METHODS

Ten competitive athletes (mean age 19.9 years) treated with open Latarjet for recurrent glenohumeral instability underwent CBRTS testing at a mean of 5.3 months postoperatively. Testing consisted of four components: 1. isometric strength, 2. isokinetic strength, 3. endurance, and 4. function. Patients failing 0 or 1 component of the test were cleared to RTP. Patients failing multiple components underwent additional deficit-based rehabilitation.

RESULTS

Of the 10 patients that tested, 4 passed their overall CBRTS test and were cleared to RTP. The remaining 6 patients failed the overall CBRTS test. Seven patients (70%) failed at least one section of the strength testing, two patients (20%) failed endurance testing, and two patients (20%) failed functional testing. At final follow-up (mean 3.6 years), 1 patient had recurrent instability (10%) and 9 patients returned to play (90%).

CONCLUSIONS

CBRTS testing may be clinically useful for return to play clearance decisions after open Latarjet procedure, as it can reveal deficits that may not be identified with time-based clearance alone.

Posterior Glenoid Bone Block Reconstruction: Indications, Techniques, and Outcomes

Posterior shoulder instability is of particular therapeutic interest, as it typically affects patients with high functional demands such as young athletes and active adults. Although posterior capsulolabral repair has high return-to-sport rates, it is associated with recurrent instability of up to 11%. Posterior glenoid bone loss and significant glenoid retroversion have been identified as risk factors for recurrent instability and failure after primary arthroscopic soft-tissue repair. Therefore, posterior glenoid bone block reconstruction may be indicated for glenoid bone loss 20% or greater (as measured by the perfect circle technique) or greater than 10% in the setting of pathologic glenoid, failed primary posterior labral repair, incompetent posterior capsular tissue, or significant risk factors for failure of soft-tissue repair. This procedure may be performed arthroscopically or with a posterior open approach using distal tibial allograft, iliac crest autograft, or scapular spine autograft. Although short-term to midterm outcomes have been promising, there remain concerns regarding long-term outcomes, with potentially high rates of late recurrence, revision, and secondary osteoarthritis.

Reversing chronic pseudoparesis secondary to massive, irreparable rotator cuff tear: superior capsular reconstruction vs. reverse total shoulder arthroplasty

INTRODUCTION

Recent studies have defined pseudoparesis as limited active forward elevation between 45° and 90° and maintained passive range of motion (ROM) in the setting of a massive rotator cuff tear (RCT). Although pseudoparesis can be reliably reversed with reverse total shoulder arthroplasty (RSA) or superior capsular reconstruction (SCR), the optimal treatment for this indication remains unknown. The purpose of this study was to compare the clinical outcomes of RSA to SCR in patients with pseudoparesis secondary to massive, irreparable RCT (miRCT).

METHODS

This was a retrospective cohort study of consecutive patients aged 40-70 years with pseudoparesis secondary to miRCT who were treated with either RSA or SCR by a single fellowship-trained shoulder surgeon from 2016 to 2021 with a minimum 12-month follow-up. Multivariate linear regression modeling was used to compare active ROM, visual analog pain scale (VAS), Subjective Shoulder Value (SSV), and American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) score between RSA and SCR while controlling for confounding variables.

RESULTS

Twenty-seven patients were included in the RSA cohort and 23 patients were included in the SCR cohort with similar mean follow-up times (26.2 ± 21.1 vs. 21.9 ± 14.7 months, respectively). The patients in the RSA group were significantly older than those in the SCR group (65.2 ± 4.4 vs. 54.2 ± 7.8 years, P < .001) and had more severe arthritis (1.8 ± 0.9 vs. 1.2 ± 0.5 Samilson-Prieto, P = .019). The pseudoparesis reversal rate among the RSA and SCR cohorts was 96.3% and 91.3%, respectively. On univariate analysis, the RSA cohort demonstrated significantly greater mean improvement in active FF (89° ± 26° vs. 73° ± 30° change, P = .048), greater postoperative SSV (91 ± 8% vs. 69 ± 25%, P < .001), lower postoperative VAS pain scores (0.6 ± 1.2 vs. 2.2 ± 2.9, P = .020), and less postoperative internal rotation (IR; 4.6° ± 1.6° vs. 6.9° ± 1.8°, P = .004) compared with SCR. On multivariate analysis controlling for age and osteoarthritis, RSA remained a significant predictor of greater SSV (β = 21.5, P = .021) and lower VAS scores (β = -1.4, P = .037), whereas SCR was predictive of greater IR ROM (β = 3.0, P = .043).

CONCLUSION

Although both RSA and SCR effectively reverse pseudoparesis, patients with RSA have higher SSV and lower pain scores but less IR after controlling for age and osteoarthritis. The results of this study may inform surgical decision making for patients who are suitable candidates for either procedure.

Transcranial Motor Evoked Potentials as a Predictive Modality for Postoperative Deficit in Cervical Spine Decompression Surgery - A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic Review and Meta-analysis.

OBJECTIVE

The purpose of this study was to evaluate whether transcranial motor evoked potential (TcMEP) alarms can predict postoperative neurologic complications in patients undergoing cervical spine decompression surgery.

METHODS

A meta-analysis of the literature was performed using PubMed, Web of Science, and Embase to retrieve published reports on intraoperative TcMEP monitoring for patients undergoing cervical spine decompression surgery. The sensitivity, specificity, and diagnostic odds ratio (DOR), of overall, reversible, and irreversible TcMEP changes for predicting postoperative neurological deficit were calculated. A subgroup analysis was performed to compare anterior vs posterior approaches.

RESULTS

Nineteen studies consisting of 4608 patients were analyzed. The overall incidence of postoperative neurological deficits was 2.58% (119/4608). Overall TcMEP changes had a sensitivity of 56%, specificity of 94%, and DOR of 19.26 for predicting deficit. Reversible and irreversible changes had sensitivities of 16% and 49%, specificities of 95% and 98%, and DORs of 3.54 and 71.74, respectively. In anterior procedures, TcMEP changes had a DOR of 17.57, sensitivity of 49%, and specificity of 94%. In posterior procedures, TcMEP changes had a DOR of 21.01, sensitivity of 55%, and specificity of 94%.

CONCLUSION

TcMEP monitoring has high specificity but low sensitivity for predicting postoperative neurological deficit in cervical spine decompression surgery. Patients with new postoperative neurological deficits were 19 times more likely to have experienced intraoperative TcMEP changes than those without new deficits, with irreversible TcMEP changes indicating a much higher risk of deficit than reversible TcMEP changes.

Defining spatiotemporal gene modules in liver regeneration using Analytical Dynamic Visual Spatial Omics Representation (ADViSOR)

BACKGROUND

The liver is the only organ with the ability to regenerate following surgical or toxicant insults, and partial hepatectomy serves as an experimental model of liver regeneration (LR). Dynamic changes in gene expression occur from the periportal to pericentral regions of the liver following partial hepatectomy; thus, spatial transcriptomics, combined with a novel computational pipeline (ADViSOR [Analytic Dynamic Visual Spatial Omics Representation]), was employed to gain insights into the spatiotemporal molecular underpinnings of LR.

METHODS

ADViSOR, comprising Time-Interval Principal Component Analysis and sliding dynamic hypergraphs, was applied to spatial transcriptomics data on 100 genes assayed serially through LR, including key components of the Wnt/β-catenin pathway at critical timepoints after partial hepatectomy.

RESULTS

This computational pipeline identified key functional modules demonstrating cell signaling and cell-cell interactions, inferring shared regulatory mechanisms. Specifically, ADViSOR analysis suggested that macrophage-mediated inflammation is a critical component of early LR and confirmed prior studies showing that Ccnd1, a hepatocyte proliferative gene, is regulated by the Wnt/β-catenin pathway. These findings were subsequently validated through protein localization, which provided further confirmation and novel insights into the spatiotemporal changes in the Wnt/β-catenin pathway during LR.

CONCLUSIONS

Thus, ADViSOR may yield novel insights in other complex, spatiotemporal contexts.

Hepatocyte β-catenin loss is compensated by Insulin-mTORC1 activation to promote liver regeneration

BACKGROUND AND AIMS

Liver regeneration (LR) following partial hepatectomy (PH) occurs via activation of various signaling pathways. Disruption of a single pathway can be compensated by activation of another pathway to continue LR. The Wnt-β-catenin pathway is activated early during LR and conditional hepatocyte loss of β-catenin delays LR. Here, we study mechanism of LR in the absence of hepatocyte-β-catenin.

APPROACH AND RESULTS

Eight-week-old hepatocyte-specific Ctnnb1 knockout mice (β-catenin ΔHC ) were subjected to PH. These animals exhibited decreased hepatocyte proliferation at 40-120 h and decreased cumulative 14-day BrdU labeling of <40%, but all mice survived, suggesting compensation. Insulin-mediated mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) activation was uniquely identified in the β-catenin ΔHC mice at 72-96 h after PH. Deletion of hepatocyte regulatory-associated protein of mTOR (Raptor), a critical mTORC1 partner, in the β-catenin ΔHC mice led to progressive hepatic injury and mortality by 30 dys. PH on early stage nonmorbid Raptor ΔHC -β-catenin ΔHC mice led to lethality by 12 h. Raptor ΔHC mice showed progressive hepatic injury and spontaneous LR with β-catenin activation but died by 40 days. PH on early stage nonmorbid Raptor ΔHC mice was lethal by 48 h. Temporal inhibition of insulin receptor and mTORC1 in β-catenin ΔHC or controls after PH was achieved by administration of linsitinib at 48 h or rapamycin at 60 h post-PH and completely prevented LR leading to lethality by 12-14 days.

CONCLUSIONS

Insulin-mTORC1 activation compensates for β-catenin loss to enable LR after PH. mTORC1 signaling in hepatocytes itself is critical to both homeostasis and LR and is only partially compensated by β-catenin activation. Dual inhibition of β-catenin and mTOR may have notable untoward hepatotoxic side effects.

Outpatient shoulder arthroplasty in the COVID-19 era: 90-day complications and risk factors

BACKGROUND

With the COVID-19 pandemic placing an increased burden on health care systems, shoulder arthroplasties are more commonly being performed as outpatient procedures. The purpose of this study was to characterize the 90-day episode-of-care complications of consecutive shoulder arthroplasties defaulted for outpatient surgery without using a prior algorithm for patient selection and to assess for their risk factors. We hypothesized that outpatient shoulder arthroplasty would be a safe procedure for all patients, regardless of patient demographics and comorbidities.

METHODS

A retrospective review of consecutive patients who underwent planned outpatient anatomic or reverse total shoulder arthroplasty between March 2020 and January 2022 with 3-month follow-up was performed. All patients were scheduled for outpatient surgery regardless of medical comorbidities. Patient demographics; pre/postoperative patient-reported outcomes including visual analog scale, subjective shoulder value, and American Shoulder and Elbow Surgeons score; pre/postoperative range of motion; and complications were collected from medical chart review. Multivariate logistic regression was used to identify predictors of the following outcomes: 1. Unplanned overnight hospital stay, 2. 90-day unplanned emergency department (ED)/clinic visit, 3. 90-day hospital readmission, 4. 90-day complications requiring revision.

RESULTS

One hundred twenty-seven patients (47% male, 17% tobacco users, 18% diabetics) with a mean age 69 ± 9 years were identified, of whom 92 underwent reverse total shoulder arthroplasty and 35 underwent anatomic total shoulder arthroplasty. All patient-reported outcomes and range of motion were significantly improved at 3 months. There were 15 unplanned overnight hospital stays (11.8%) after the procedure. Within 90 days postoperatively, there were 17 unplanned ED/clinic visits (13.4%), 7 hospital readmissions (5.5%), and 4 complications requiring revision (3.1%). Factors predictive of unplanned overnight stay included age above 70 years (odds ratio [OR], 36.80 [95% confidence interval [CI], 2.20-615.49]; P = .012), tobacco use (OR, 12.90 [95% CI, 1.23-135.31]; P = .033), and American Society of Anesthesiologists status of 3 (OR, 13.84 [95% CI, 1.22-156.57]; P = .034). The only factor predictive of unplanned ED/clinic visit was age over 70 years old (OR, 7.52 [95% CI, 1.26-45.45]; P = .027). No factors were predictive of 90-day hospital readmission or revision.

CONCLUSION

Outpatient shoulder arthroplasty is a safe procedure with excellent outcomes and low rates of readmissions and can be considered as the default plan for all patient undergoing shoulder arthroplasty. Patients who are above 70 years of age, use tobacco, and have ASA score of 3, however, may be less suitable for outpatient arthroplasty and should be counseled regarding the higher risk of unplanned overnight hospitalization.

A multilayered scaffold for regeneration of smooth muscle and connective tissue layers

Tissue regeneration often requires recruitment of different cell types and rebuilding of two or more tissue layers to restore function. Here, we describe the creation of a novel multilayered scaffold with distinct fiber organizations-aligned to unaligned and dense to porous-to template common architectures found in adjacent tissue layers. Electrospun scaffolds were fabricated using a biodegradable, tyrosine-derived terpolymer, yielding densely-packed, aligned fibers that transition into randomly-oriented fibers of increasing diameter and porosity. We demonstrate that differently-oriented scaffold fibers direct cell and extracellular matrix (ECM) organization, and that scaffold fibers and ECM protein networks are maintained after decellularization. Smooth muscle and connective tissue layers are frequently adjacent in vivo; we show that within a single scaffold, the architecture supports alignment of contractile smooth muscle cells and deposition by fibroblasts of a meshwork of ECM fibrils. We rolled a flat scaffold into a tubular construct and, after culture, showed cell viability, orientation, and tissue-specific protein expression in the tube were similar to the flat-sheet scaffold. This scaffold design not only has translational potential for reparation of flat and tubular tissue layers but can also be customized for alternative applications by introducing two or more cell types in different combinations.

Processed human amniotic fluid retains its antibacterial activity

BACKGROUND

Human amniotic fluid (AF) contains numerous nutrients, trophic factors and defense proteins that provide a nurturing and protective environment for fetal development. Based on reports that AF has antibacterial, anti-inflammatory and regenerative properties, we designed a novel method to process AF for use in clinical care.

METHODS

Six randomly selected lots of processed AF (pAF) were examined to determine whether they retained their antibacterial activity against a panel of wound-associated pathogens E. faecium, S. aureus, K. pneumoniae, A. baumannii, P. aeruginosa, and E. aerogenes (ESKAPE). To identify proteins in pAF that might be responsible for its antibacterial activity, three different lots of pAF were analyzed with quantitative cytokine arrays that consisted of 400 unique human proteins. One protein identified by microarrays, lactoferrin, and a second prominent antibacterial protein that was not identified by microarrays, lysozyme, were examined by depletion experiments to determine their contribution to the antibacterial activity of pAF.

RESULTS

All six lots of pAF exhibited antibacterial activity against ESKAPE microorganisms, especially against the pathogens predominately found in chronic wounds (i.e. S. aureus and P. aeruginosa). Thirty-one of the peptides on the microarray were annotated as having antibacterial activity and 26 of these were detected in pAF. Cystatin C and lactoferrin were among the most highly expressed antibacterial proteins in pAF. Cystatin C and lactoferrin were confirmed by ELISA to be present in pAF along with lysozyme. Immunoprecipitation of lactoferrin and lysozyme reduced, but did not abolish the antibacterial activities of pAF.

CONCLUSION

Our data demonstrate that pAF maintains antibacterial activity via the preservation of antibacterial proteins against a broad spectrum of wound-associated pathogens.

Extracellular matrix derived from chondrocytes promotes rapid expansion of human primary chondrocytes in vitro with reduced dedifferentiation

A significant expansion of autologous chondrocytes in vitro is required for cell-based cartilage repair. However, the in vitro expansion of chondrocytes under standard culture conditions inevitably leads to the dedifferentiation of chondrocytes and contributes to suboptimal clinical outcomes. To address this challenge, we focused our efforts on developing an improved in vitro expansion protocol, which shortens the expansion time with decreased dedifferentiation. It is known that the tissue microenvironment plays a critical role in regulating the cellular functions of resident cells and provides guidance in tissue-specific regeneration. We hypothesized that chondrocyte extracellular matrix (ECM) mimics a native microenvironment and that it may support chondrocyte expansion in vitro. To test this hypothesis, we prepared decellularized ECMs from allogeneic human articular chondrocytes (HAC) (AC-ECM) and bone marrow stromal cells (BM-ECM) and studied their effects on the in vitro expansion of primary HAC. The differential composition and physical properties of these two ECMs were revealed by mass spectrometry and atomic force microscopy. Compared with standard tissue culture polystyrene (TCP) or BM-ECM, HAC cultured on AC-ECM proliferated faster and maintained the highest ratio of COL2A1/COL1A1. Furthermore, a pellet culture study demonstrated that cells expanded on AC-ECM produced a more cartilage-like ECM than cells expanded on BM-ECM or TCP. This is the first report on modulating chondrocyte expansion and dedifferentiation using cell type-specific ECM and on identifying AC-ECM as a preferred substrate for in vitro expansion of HAC cell-based therapies. STATEMENT OF SIGNIFICANCE: To reduce the dedifferentiation of chondrocytes during in vitro expansion, cell type-specific extracellular matrix (ECM), which mimics a native microenvironment, was prepared from human articular chondrocytes (AC-ECM) or bone marrow stromal cells (BM-ECM). As demonstrated by mass spectrometry and atomic force microscopy, AC-ECM and BM-ECM have differential ECM compositions and physical characteristics. Human articular chondrocytes (HAC) expanded faster and maintained a better chondrocyte phenotype on AC-ECM than on BM-ECM or a standard culture surface. AC-ECM has potential to be developed for expanding HAC for cell-based therapies.

Antimicrobial Peptides Secreted From Human Cryopreserved Viable Amniotic Membrane Contribute to its Antibacterial Activity

Chronic wounds remain a large problem in the field of medicine and are often associated with risk of infection and amputation. Recently, a commercially available human cryopreserved viable amniotic membrane (hCVAM) has been shown to effectively promote wound closure and reduce wound-related infections. A sprevious study indicates that hCVAM can inhibit the growth of bacteria associated with chronic wounds. In the present study, we investigated the mechanism of hCVAM antimicrobial activity. Our data demonstrate that antimicrobial activities against common pathogens in chronic wounds such as P.aeruginosa, S.aureus and Methicillin-resistant S.aureus (MRSA) are mediated via the secretion of soluble factors by viable cells in hCVAM and that these factors are proteins in nature. Further, we show that genes for antimicrobial peptides (AMPs) including human beta-defensins (HBDs) are expressed by hCVAM and that expression levels positively correlate with antimicrobial activity of hCVAM. At the protein level, our data indicate that HBD2 and HBD3 are secreted by hCVAM and directly contribute to its activity against P. aeruginosa. These data provide evidence that soluble factors including AMPs are hCVAM antimicrobial agents and are consistent with a role for AMPs in mediating antimicrobial properties of the membrane.