Attenuating Chronic Fibrosis: Decreasing Foreign Body Response with Acellular Dermal Matrix

The application of small intestinal submucosa in tissue regeneration

The distinctive three-dimensional architecture, biological functionality, minimal immunogenicity, and inherent biodegradability of small intestinal submucosa extracellular matrix materials have attracted considerable interest and found wide-ranging applications in the domain of tissue regeneration engineering. This article presents a comprehensive examination of the structure and role of small intestinal submucosa, delving into diverse preparation techniques and classifications. Additionally, it proposes approaches for evaluating and modifying SIS scaffolds. Moreover, the advancements of SIS in the regeneration of skin, bone, heart valves, blood vessels, bladder, uterus, and urethra are thoroughly explored, accompanied by their respective future prospects. Consequently, this review enhances our understanding of the applications of SIS in tissue and organ repair and keeps researchers up-to-date with the latest research advancements in this area.

Omental coating attenuates implant-induced foreign body reaction in rats

The objective of this study is to clarify whether the omental coating can effectively attenuate foreign body reaction (FBR) induced by implanted materials. Male Sprague-Dawley rats were injected with polydextran particle slurry intraperitoneally to activate the omentum. 7 days later, polyether polyurethane sponge discs were implanted subcutaneously on each side of the rat's back as the foreign implants to induce FBR. The next day, omental transposition were performed. The disc on the left side of each rat's back was wrapped with omental flap (omental group); the disc on the right side was untreated (control group). All discs were removed 21 days after implantation and assessed by determining the components of the fibrovascular tissue (angiogenesis, inflammation, foreign body giant cells (FBGCs) aggregation and fibrogenesis). In implants in omental group, micro vessel density (MVD), Hemoglobin (Hb) content and VEGF levels (pro-angiogenic cytokine) were increased when compared with implants from control group. Inflammatory parameters (IL-1β; macrophage accumulation-NAG activity; neutrophil accumulation- MPO levels) were decreased in implants after omental coating. Also, collagen deposition, fibrous capsule thickness, and FBGCs decreased in implants from omental group. However, intra-implant levels of TNF-α and TGF-β1 were not different after omental coating. Our findings showed for the first time that the omental coating around the implants attenuate the adverse FBR, it may be critical in developing new strategies to control FBR and improve the function and performance of the implanted materials.

Investigating Immunomodulatory Biomaterials for Preventing the Foreign Body Response

Implantable biomaterials represent the forefront of regenerative medicine, providing platforms and vessels for delivering a creative range of therapeutic benefits in diverse disease contexts. However, the chronic damage resulting from implant rejection tends to outweigh the intended healing benefits, presenting a considerable challenge when implementing treatment-based biomaterials. In response to implant rejection, proinflammatory macrophages and activated fibroblasts contribute to a synergistically destructive process of uncontrolled inflammation and excessive fibrosis. Understanding the complex biomaterial-host cell interactions that occur within the tissue microenvironment is crucial for the development of therapeutic biomaterials that promote tissue integration and minimize the foreign body response. Recent modifications of specific material properties enhance the immunomodulatory capabilities of the biomaterial and actively aid in taming the immune response by tuning interactions with the surrounding microenvironment either directly or indirectly. By incorporating modifications that amplify anti-inflammatory and pro-regenerative mechanisms, biomaterials can be optimized to maximize their healing benefits in harmony with the host immune system.

A Review: Methodologies to Promote the Differentiation of Mesenchymal Stem Cells for the Regeneration of Intervertebral Disc Cells Following Intervertebral Disc Degeneration

Intervertebral disc (IVD) degeneration (IDD), a highly prevalent pathological condition worldwide, is widely associated with back pain. Treatments available compensate for the impaired function of the degenerated IVD but typically have incomplete resolutions because of their adverse complications. Therefore, fundamental regenerative treatments need exploration. Mesenchymal stem cell (MSC) therapy has been recognized as a mainstream research objective by the World Health Organization and was consequently studied by various research groups. Implanted MSCs exert anti-inflammatory, anti-apoptotic, and anti-pyroptotic effects and promote extracellular component production, as well as differentiation into IVD cells themselves. Hence, the ultimate goal of MSC therapy is to recover IVD cells and consequently regenerate the extracellular matrix of degenerated IVDs. Notably, in addition to MSC implantation, healthy nucleus pulposus (NP) cells (NPCs) have been implanted to regenerate NP, which is currently undergoing clinical trials. NPC-derived exosomes have been investigated for their ability to differentiate MSCs from NPC-like phenotypes. A stable and economical source of IVD cells may include allogeneic MSCs from the cell bank for differentiation into IVD cells. Therefore, multiple alternative therapeutic options should be considered if a refined protocol for the differentiation of MSCs into IVD cells is established. In this study, we comprehensively reviewed the molecules, scaffolds, and environmental factors that facilitate the differentiation of MSCs into IVD cells for regenerative therapies for IDD.