The Immune System and Its Contribution to Variability in Regenerative Medicine

Abstract

The immune system plays a critical role in directing tissue repair and regeneration outcomes. Tissue engineering technologies that are designed to promote new tissue growth will therefore be impacted by immune factors that are present in patients both locally at the site of intervention and systemically. The immune state of patients can be influenced by many factors, including infection, nutrition, and other disease comorbidities. As a result, the immune state is highly variable and may be a source of variability in tissue-engineered products in the clinic, which is not found in preclinical models. In this review, we will summarize key immune cells and evidence of their activity in tissue repair and potential in tissue engineering systems. We also discuss how clinical translation of tissue engineering strategies, in particular stem cells, helped elucidate the importance of the immune system. With increased understanding of the immune system's role in repair and tissue engineering systems, it will likely become a therapeutic target and component of future therapies.

Keywords: biomaterials; clinical translation; immune response; immune state; immune variability; tissue engineering.

FIG. 1.

Several immune cell populations orchestrate wound repair in the presence of a scaffold. This schematic highlights the immune cells known to play a role in clinical outcomes, including NK cells, innate lymphoid cells, T cells, fibroblasts, B cells, eosinophils, and monocytes/macrophages. NK, natural killer.

FIG. 2.

An individual's nonheritable immune influences include antigen/allergy exposure, age and history of infections, diet/microbiota, and previous injury. Together, nonheritable influences demonstrate significant impact on an individual's immune state.