How have biologics revolutionized organ/tissue transplantation and regenerative medicine?

Regenerative medicine focuses on structural and functional organ and tissue repair using either biologics alone or a combination of biologics and synthetic materials. From a therapeutic research perspective, the ultimate goal of regenerative medicine is provide more accessible and less risky alternatives to standard organ/tissue transplantation. 

Initial attempts directly introducing biologic agents with regenerative potential (i.e., stem cells, growth factors) into sites of injury were met with limited and transient success. Consequently, regenerative medicine today focuses on not only generating the correct cell type(s) to replace the damaged or dead cells at the injured site, but also placing them on a scaffold or graft that recapitulates the natural microenvironment of the healthy tissue. This can be done in several ways. 

A synthetic or semi-synthetic scaffold can be implanted directly on the site of injury in order to give endogenous regenerative cells a favorable environment. This scaffold can also be seeded with biologics – such as cells, growth factors, or cytokines – in order to trigger or augment natural growth responses.^1,2 Alternatively, in situations where immediate functional recovery is paramount (i.e., skin integrity, muscle contraction, organ failure), cells can be seeded on a scaffold ex vivo and cultured to generate a functional tissue structure, which is then implanted. In both scenarios, because the cells are obtained from an autologous source, the risk of immune-mediated graft/transplant rejection is diminished.^1,2

References:
(1) G.J. Christ et al., “The pharmacology of regenerative medicine,” Pharmacol Rev, 65(3):1091-1133, 2013.
(2) K. Yano et al., “Regulatory approval for autologous human cells and tissue products in the United States, the European Union, and Japan,” Regen Ther, 1:45-56, 2015.