Fibronectin matrix assembly and TGFβ1 presentation for chondrogenesis of patient derived pericytes for microtia repair.

Tissue engineered cartilage for external ear reconstruction of congenital deformities, such as microtia or resulting from trauma, remains a significant challenge for plastic and reconstructive surgeons. Current strategies involve harvesting autologous costal cartilage or expanding autologous chondrocytes ex vivo. However, these procedures often lead to donor site morbidity and a cell source with limited expansion capacity. Stromal stem cells such as perivascular stem cells (pericytes) offer an attractive alternative cell source, as they can be isolated from many human tissues, readily expanded in vitro and possess chondrogenic differentiation potential. Here, we successfully isolate CD146+ pericytes from the microtia remnant from patients undergoing reconstructive surgery (Microtia pericytes; MPs). Then we investigate their chondrogenic potential using the polymer poly(ethyl acrylate) (PEA) to unfold the extracellular matrix protein fibronectin (FN). FN unfolding exposes key growth factor (GF) and integrin binding sites on the molecule, allowing tethering of the chondrogenic GF transforming growth factor beta 1 (TGFβ1). This system leads to solid-phase, matrix-bound, GF presentation in a more physiological-like manner than that of typical chondrogenic induction media (CM) formulations that tend to lead to off-target effects. This simple and controlled material-based approach demonstrates similar chondrogenic potential to CM, while minimising proclivity toward hypertrophy, without the need for complex induction media formulations.