Reaction of Mast Cells in the Zone of Polypropylene Mesh Implantation

Mast Cell-Biomaterial Interactions and Tissue Repair

Tissue engineers often use biomaterials to provide structural support along with mechanical and chemical signals to modulate the wound healing process. Biomaterials that are implanted into the body interact with a heterogeneous and dynamic inflammatory environment that is present at the site of injury. Whether synthetically derived, naturally derived, or a combination of both, it is important to assess biomaterials for their ability to modulate inflammation to understand their potential clinical use. One important, but underexplored cell in the context of biomaterials is the mast cell (MC). MCs are granulocytic leukocytes that engage in a variety of events in both the innate and adaptive immune systems. Although highly recognized for their roles in allergic reactions, MCs play an important role in wound healing by recognizing antigens through pattern recognition receptors and the high-affinity immunoglobulin E receptor (FceRI) and releasing granules that affect cell recruitment, fibrosis, extracellular matrix deposition, angiogenesis, and vasculogenesis. MCs also mediate the foreign body response, contributing to the incorporation or rejection of implants. Studies of MC-biomaterial interactions can aid in the elucidation of MC roles during the host tissue response and tissue repair. This review is designed for those in the tissue engineering and biomaterial fields who are interested in exploring the role MCs may play in wound-biomaterial interactions and wound healing. With this review, we hope to inspire more research in the MC-biomaterial space to accelerate the design and construction of optimized implants. Impact statement Mast cells (MCs) are highly specialized inflammatory cells that have crucial, but not fully understood, roles in wound healing and tissue repair. Upon stimulation, they recognize foreign antigens and release granules that help orchestrate the inflammatory response after tissue damage or biomaterial implantation. This review summarizes the current use of MCs in biomaterial research along with literature from the past decade focusing on MC interactions with materials used for tissue repair and regeneration. Studying MC-biomaterial interactions will help (i) further understand the process of inflammation and (ii) design biomaterials and tissue-engineered constructs for optimal repair and regeneration.

Control of innate immune response by biomaterial surface topography, energy, and stiffness

As the focus of implantable biomaterials has shifted from bioinert implants to bioactive designs, recent research has highlighted the complex interactions between cell physiologic systems and material properties, particularly physical cues. From the cells known to interact with implanted biomaterials, the response of the immune system has been a critical target of study recently. Here, we review studies characterizing the response of innate immune cells to various material cues, particularly of those at the surface of implanted materials.The innate immune system consists of cell types with various roles in inflammation. Neutrophils and macrophages serve both phagocytic and signaling roles, especially early in the inflammatory phase of biomaterial implantation. These cell types ultimately dictate the outcome of implants as chronic inflammation, fibrosis, or integration. Other cell types like dendritic cells, mast cells, natural killer cells, and innate lymphoid cells may also serve an immunomodulatory role in the biomaterial context. This review highlights recent advances in our understanding of the role of innate immunity in the response to implantable biomaterials as well as key mechanobiological findings in innate immune cells underpinning these advances. STATEMENT OF SIGNIFICANCE: This review highlights recent advances in the understanding of the role of innate immunity in the response to implantable biomaterials, especially in neutrophils and macrophages, as well as key mechanobiological findings in innate immune cells underpinning these advances. Here we discuss how physicochemical properties of biomaterials control innate immune cell behavior.

Activity of Gas Transmitters in Vessels of the Anterior Abdominal Wall after Implantation of a Polypropylene Mesh

The distribution of NO and H₂S in the arterial vessels of the anterior abdominal wall after implantation of a polypropylene mesh was studied by immunohistochemical methods at different stages of healing of the surgical wound in mature male Wistar rats. The presence of enzymes of NO and H₂S synthesis in the wall of arterial vessels of the soft tissues of the anterior abdominal wall has been established. It has been shown that endothelial NO synthase is localized exclusively in the endothelium of both large and small vessels. Cystathionine γ lyase in small vessels is located only in the endothelial lining, whereas in large arteries and vessels of medium caliber, it is located in the endothelium and in myocytes. Inducible NO synthase appears in the artery wall only in animals with implanted polypropylene mesh by day 5 of the postoperative period, reaching the maximum by day 10. The content and localization of cystathionine γ lyase in the vascular wall of sham-operated and experimental rats did not much differ from the control values.