Preparation and Use of Decellularized Extracellular Matrix for Tissue Engineering

The multidisciplinary fields of tissue engineering and regenerative medicine have the potential to revolutionize the practise of medicine through the abilities to repair, regenerate, or replace tissues and organs with functional engineered constructs. To this end, tissue engineering combines scaffolding materials with cells and biologically active molecules into constructs with the appropriate structures and properties for tissue/organ regeneration, where scaffolding materials and biomolecules are the keys to mimic the native extracellular matrix (ECM). For this, one emerging way is to decellularize the native ECM into the materials suitable for, directly or in combination with other materials, creating functional constructs. Over the past decade, decellularized ECM (or dECM) has greatly facilitated the advance of tissue engineering and regenerative medicine, while being challenged in many ways. This article reviews the recent development of dECM for tissue engineering and regenerative medicine, with a focus on the preparation of dECM along with its influence on cell culture, the modification of dECM for use as a scaffolding material, and the novel techniques and emerging trends in processing dECM into functional constructs. We highlight the success of dECM and constructs in the in vitro, in vivo, and clinical applications and further identify the key issues and challenges involved, along with a discussion of future research directions.

Human adipose and synovial mesenchymal stem cells improve osteoarthritis in rats by reducing chondrocyte reactive oxygen species and inhibiting inflammatory response

Background

We explored the therapeutic effects of Adipose‐derived mesenchymal stem cells (ADMSCs) and Synovial‐derived mesenchymal stem cells (SDMSCs) on osteoarthritis (OA).

Methods

SDMSCs and ADMSCs were co‐cultured with chondrocytes and stimulated with interleukin (IL)‐1β. An OA model was established on rats by intra‐articular injection with ADMSCs and SDMSCs. After 8 weeks, the joint diameter difference was detected, and histological staining was used to observe the pathological changes in cartilage tissue. Enzyme‐linked immunosorbent assay (ELISA) was used to detect the expressions of IL‐6, tumor necrosis factor (TNF)‐α and IL‐1β in joint fluid. The expressions of COL2A1, Aggrecan, Matrix metalloproteinase (MMP)‐13, SOX9, IL‐6, TNF‐α and IL‐1β were detected by qRT‐PCR and Western blotting in cartilage tissue. Reactive oxygen species (ROS) content in cells and cartilage tissues was detected by ROS kit.

Results

SDMSCs and ADMSCs co‐cultured with chondrocytes could reduce MMP‐13 expression, increase the expressions of COL2A1, Aggrecan and SOX9, as well as reverse the effects of IL‐1β on promoting ROS content and inflammatory factors levels. After the OA model was established, the injection of ADMSCs and SDMSCs reduced the differences in joint diameter and tissue lesions in OA rats. The OA model led to increased levels of IL‐6, TNF‐α and IL‐1β in joint fluid and cartilage tissue, while the injection of ADMSCs and SDMSCs inhibited the inflammatory factor levels in OA rats, and increased the expressions of COL2A1, Aggrecan and SOX9 in OA rats.

Conclusion

ADMSCs and SDMSCs improve osteoarthritis in rats by reducing chondrocyte ROS and inhibiting inflammatory response.

Comparison of the Chondrogenic Differentiation Potential of Equine Synovial Membrane-Derived and Bone Marrow-Derived Mesenchymal Stem Cells

Focal cartilage injury occurs commonly and often precipitates OA. Mesenchymal stem cells (MSCs) may be useful for repairing cartilage lesions, thereby preventing joint degeneration. Although MSCs isolated from bone marrow have been shown to have chondrogenic potential, synovial membrane-derived MSCs (SM-MSCs) may have superior chondrogenic abilities due to a common progenitor cell between synovium and cartilage. The objective of this study was to directly compare the immunophenotype, proliferative capabilities, and chondrogenic potential of equine SM-MSCs and bone marrow-derived MSCs (BM-MSCs). In order to do this, MSCs were isolated from synovial membrane and bone marrow collected from 6 adult horses. Flow cytometric analysis was used to assess cell surface marker expression including CD29, CD44, CD90, CD105, CD45, CD-79α, MHCI, and MHCII. Proliferation rates and doubling time were quantified in P1 and P2 cells. Trilineage differentiation assays were performed. MSC pellets were cultured in chondrogenic induction media for 28 days. Pellets were stained with toluidine blue to assess proteoglycan deposition. Expression of the chondrogenic-related genes ACAN, COL2b, and SOX9 was quantified using qRT-PCR. The immunophenotypes of BM-MSCs and SM-MSCs were similar with both cell types being positive for expression of stem cell markers (CD29, CD44, CD90, CD105, and MHCI) and negative for exclusion markers (CD45 and CD79α). Although SM-MSCs did not express the exclusion marker, MHCII, expression of MHCII was moderate in BM-MSCs. Overall, chondrogenic differentiation was not significantly between the cell types with histologic parameters, proteoglycan content and gene expression being similar. BM-MSCs showed enhanced osteogenic differentiation compared to SM-MSCs. Synovial membrane is a feasible source of MSCs in the horse, however, superior chondrogenesis in vitro should not be expected under currently described culture conditions.

Synovium extra cellular matrices seeded with transduced mesenchymal stem cells stimulate chondrocyte maturation in vitro and cartilage healing in clinically-induced rat-knee lesions in vivo

Osteoarthritis (OA) is a progressive disease associated with cartilage injury and its inherently limited repair capability. Synovium-based cellular constructs (sConstructs) are proposed as possible treatments. Equine sConstructs were produced from decellularized synovium-based extracellular matrix scaffolds (sECM) seeded with synovium-derived mesenchymal stem cells (sMSC), and engineered to express green fluorescent protein (GFP), or bone morphogenetic protein-2 (BMP-2). Survival, distribution, and chondrogenic potential of the sConstructs in vitro and in vivo were assessed. sConstructs in co-culture with chondrocytes increased chondrocyte proliferation, viability, and Col II production, greatest in BMP-2-sConstructs. Chondrocyte presence increased the production of hyaluronic acid (HA), proteoglycan (PG), and BMP-2 by the sConstructs in a positive feedback loop. sECM alone, or GFP- or BMP-2-sConstructs were implanted in synovium adjacent to clinically created full-thickness rat-knee cartilage lesions. At 5 weeks, the lesion area and implants were resected. Gross anatomy, adjacent articulate cartilage growth and subchondral bone repair were scored; and peripheral, central and cartilage lesion measurements taken. For all scores and measurements, sConstruct implants were significantly greater than controls, greatest with the BMP-2-sConstructs. Immunohistochemistry demonstrated migration of endogenous cells into the sECM, with greater cellularity in the constructs with intense positive GFP staining confirming engraftment of implanted sMSC and continued gene expression. In summary, exposing cartilage to sConstructs was chondrogenic in vitro and in vivo, and resulted in substantially increased growth in vivo. This effect was mediated, in part, by soluble ECM and cell factors and upregulation of anabolic growth proteins, such as BMP-2. This work is "proof of concept" that sConstructs surgically implanted adjacent to cartilage damage can significantly improve cartilage and subchondral bone repair, and potentially prevent the progression of OA.