Silvia S. Chen

Human placenta hydrogel reduces scarring in a rat model of cardiac ischemia and enhances cardiomyocyte and stem cell cultures.

INTRODUCTION Xenogeneic extracellular matrix (ECM) hydrogels have shown promise in remediating cardiac ischemia damage in animal models, yet analogous human ECM hydrogels have not been well development. An original human placenta-derived hydrogel (hpECM) preparation was thus generated for assessment in cardiomyocyte cell culture and therapeutic cardiac injection applications. METHODS AND RESULTS Hybrid orbitrap-quadrupole mass spectrometry and ELISAs showed hpECM to be rich in collagens, basement membrane proteins, and regenerative growth factors (e.g. VEGF-B, HGF). Human induced pluripotent stem cell (iPSC)-derived cardiomyocytes synchronized and electrically coupled on hpECM faster than on conventional cell culture environments, as validated by intracellular calcium measurements. In vivo, injections using biotin-labeled hpECM confirmed its spatially discrete localization to the myocardium proximal to the injection site. hpECM was injected into rat myocardium following an acute myocardium infarction induced by left anterior descending artery ligation. Compared to sham treated animals, which exhibited aberrant electrical activity and larger myocardial scars, hpECM injected rat hearts showed a significant reduction in scar volume along with normal electrical activity of the surviving tissue, as determined by optical mapping. CONCLUSION Placental matrix and growth factors can be extracted as a hydrogel that effectively supports cardiomyocytes in vitro, and in vivo reduces scar formation while maintaining electrophysiological activity when injected into ischemic myocardium. STATEMENT OF SIGNIFICANCE This is the first report of an original extracellular matrix hydrogel preparation isolated from human placentas (hpECM). hpECM is rich in collagens, laminin, fibronectin, glycoproteins, and growth factors, including known pro-regenerative, pro-angiogenic, anti-scarring, anti-inflammatory, and stem cell-recruiting factors. hpECM supports the culture of cardiomyocytes, stem cells and blood vessels assembly from endothelial cells. In a rat model of myocardial infarction, hpECM injections were safely deliverable to the ischemic myocardium. hpECM injections repaired the myocardium, resulting in a significant reduction in infarct size, more viable myocardium, and a normal electrophysiological contraction profile. hpECM thus has potential in therapeutic cardiovascular applications, in cellular therapies (as a delivery vehicle), and is a promising biomaterial for advancing basic cell-based research and regenerative medicine applications.

Characterization of a Cryopreserved Split-Thickness Human Skin Allograft-TheraSkin.

OBJECTIVE:The purpose of this study was to examine the characteristics of a cryopreserved split-thickness skin allograft produced from donated human skin and compare it with fresh, unprocessed human split-thickness skin. BACKGROUND:Cutaneous wound healing is a complex and organized process, where the body re-establishes the integrity of the injured tissue. However, chronic wounds, such as diabetic or venous stasis ulcers, are difficult to manage and often require advanced biologics to facilitate healing. An ideal wound care product is able to directly influence wound healing by introducing biocompatible extracellular matrices, growth factors, and viable cells to the wound bed. MATERIALS AND METHODS:TheraSkin (processed by LifeNet Health, Virginia Beach, Virginia, and distributed by Soluble Systems, Newport News, Virginia) is a minimally manipulated, cryopreserved split-thickness human skin allograft, which contains natural extracellular matrices, native growth factors, and viable cells. The authors characterized TheraSkin in terms of the collagen and growth factor composition using ELISA, percentage of apoptotic cells using TUNEL analysis, and cellular viability using alamarBlue assay (Thermo Fisher Scientific, Waltham, Massachusetts), and compared these characteristics with fresh, unprocessed human split-thickness skin. RESULTS:It was found that the amount of the type I and type III collagen, as well as the ratio of type I to type III collagen in TheraSkin, is equivalent to fresh unprocessed human split-thickness skin. Similar quantities of vascular endothelial growth factor, insulinlike growth factor 1, fibroblast growth factor 2, and transforming growth factor &bgr;1 were detected in TheraSkin and fresh human skin. The average percent of apoptotic cells was 34.3% and 3.1% for TheraSkin and fresh skin, respectively. CONCLUSIONS:Cellular viability was demonstrated in both TheraSkin and fresh skin.

Demineralized bone matrix fibers formable as general and custom 3D printed mold-based implants for promoting bone regeneration.

INTRODUCTION Bone repair frequently requires time-consuming implant construction, particularly when using un-formed implants with poor handling properties. We therefore developed osteoinductive, micro-fibrous surface patterned demineralized bone matrix (DBM) fibers for engineering both defect-matched and general three-dimensional implants. METHODS AND RESULTS Implant molds were filled with demineralized human cortical bone fibers there were compressed and lyophilized, forming mechanically strong shaped DBM scaffolds. Enzyme linked immunosorbent assays and mass spectrometry confirmed that DBM fibers contained abundant osteogenic growth factors (bone morphogenetic proteins, insulin-like growth factor-I) and extracellular matrix proteins. Mercury porosimetry and mechanical testing showed interconnected pores within the mechanically stable, custom DBM fiber scaffolds. Mesenchymal stem cells readily attached to the DBM and showed increasing metabolic activity over time. DBM fibers further increased alkaline phosphatase activity in C2C12 cells. In vivo, DBM implants elicited osteoinductive potential in a mouse muscle pouch, and also promoted spine fusion in a rat arthrodesis model. SIGNIFICANCE DBM fibers can be engineered into custom-shaped, osteoinductive and osteoconductive implants with potential for repairing osseous defects with precise fitment, potentially reducing operating time. By providing pre-formed and custom implants, this regenerative allograft may improve patient outcomes following surgical bone repair, while further advancing personalized orthopedic and craniomaxillofacial medicine using three-dimensional-printed tissue molds.