Novel therapies for cartilage regeneration have had limited success. Chondrogenic differentiation of mesenchymal stem cells (MSCs) under load is different to that observed during classical static culture conditions. This is highly clinically relevant, considering that patients receive weight-bearing rehabilitation therapy following cartilage repair. Additionally, as most in vitro cartilage repair studies are performed under static conditions, the lack of mechanical stimulation may explain why it has been challenging to reproduce promising in vitro results in vivo. Marrow stimulation techniques, such as microfracture, are the most commonly used clinical approach for cartilage repair with unpredictable results. Using a unique in vivo kinematic join simulating bioreactor, we have previously shown that while complex multiaxial load induces hMSC chondrogenesis, it also induces the expression of a number of soluble molecules not typically found under static culture conditions. This identified novel mechanically induced targets, such as nitric oxide (NO), that are potentially clinically relevant. Within this project we aim to better understand the role of mechanical load on the molecules induced during human MSC chondrogenesis vs standard conditions (static and with TGF-beta). We will identify new potential treatment targets, while investigating the biological function of nitric oxide.
This project aims to establish the functional modulation of non-cartilage cell types by mechanically stimulated MSC secretome, thus providing valuable further insight into the pathology of joint destruction.
Using a design of experiments (DoE) approach, we have established optimal loading conditions to a) increase TGFβ production and b) increase the mechanical activation of latent TGFβ protein. Interestingly the protocol optimal for expression is not the same as that optimal for activation. This suggests that rehabilitation protocols may need to increase in complexity to improve cellular differentiation.
Swiss National Funds (nr 31003A_179438 / 1), Funding: CHF 417'720, Period: 08/2018-07/2022
Snedeker Jess G (Prof, PhD), ETH Zürich, Switzerland