Oscillating hydrogel based bioreactors for chondrogenic differentiation of mesenchymal stem cells.

摘要

Harnessing the differentiative potential of stem cells for use in tissue repair could be a powerful therapy for debilitating diseases. However, one of the bottlenecks of stem cell based therapeutics and tissue engineering is inefficient and homogeneous stem cell differentiation. Various physico-chemical cues such as mechanical strain, chemical components, and soluble factors have been shown to direct stem cell differentiation. This study developed a multifunctional polymer-based artificial ECM replicating the multifunctional characteristics of native ECM to understand the physico-chemical cues present in a 3D environment. Specifically, we have developed a synthetic hydrogel that acts as a scaffold and bioreactor providing dynamic mechanical cues and structural support to cells. A heating device was used to induce ∼5% volume strain by applying temperature oscillations to thermoresponsive hydrogels. Human mesenchymal stem cells (hMSCs) were encapsulated in P[MEO2MA-OEGMA-EGDA] (MO) (10 and 20% Mw PEG: 3400) and PEGDA(15% Mw PEG: 10000) hydrogels and cultured with and without TGFa-1. Fluorescent particle tracking was used to measure realtime volume strains of acellular and cellular hydrogels under temperature oscillations and verified with swelling ratios. hMSCs produced cartilaginous ECM as evidenced from histological and biochemical analysis. Realtime PCR was used to characterize the expression of various chondrogenic markers, indicating optimal chondrogenic differentiation with 1 hour stimulated PEGDA (15% PEG) hydrogels and TGFa-1. Due to static mechanical strains induced by high crosslinking density and confined heating chambers, enhanced chondrogenic differentiation was limited for all gels. Overall, this study demonstrated the potential use of polymer-based synthetic bioactuators for stem cell differentiation.