Cell dedifferentiation in the ceiling culture system: regulators of cell matrix remodelling

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This NSERC Discovery program was initially funded in 2011. It is based on the process of adipocyte dedifferentiation through ceiling culture. The General Objective of the present renewal application is to characterize the dedifferentiation process of mature adipocytes and the fibroblast-like cells generated by the ceiling culture approach. For this coming term, we propose two specific aims that represent the direct and logical continuation of findings that were generated in the first term of this grant. Specific Aim #1: To characterize the role of DPP4 and FAP in adipocyte dedifferentiation. Pharmacological inhibitors of FAP and DPP4 as well as cells isolated from Fap-deficient mice will be used to establish and characterize the importance of these molecules in adipocyte dedifferentiation in ceiling cultures. Based on preliminary observations, we hypothesize that DPP4 and FAP inhibition or absence partially impairs the process of dedifferentiation. Specific Aim #2: To characterize the role of TGF-ß in the process of adipocyte dedifferentiation. Pharmacological inhibitors and cells isolated from mouse models deficient in TGF-ß1 signalling will be used to characterize the impact of this cytokine on adipocyte dedifferentiation in ceiling cultures. Based on preliminary observations, we hypothesize that TGF-ß1 is responsible for the main causal signal inducing dedifferentiation. The challenge of the present proposal lies in the characterization of a cell process that may be involved in the regulation of tissue cell dynamics in several organs and species. Much like in the first term of this grant, this new endeavor will require development of new approaches such as collagen suspension cultures and possibly real time monitoring of cell function using impedance-based measurements (Research Tools and Instruments grant application submitted). These technical challenges clearly relate to engineering. Although we propose a project that does, indeed, relate to biological sciences, it is not a health-related proposal. Our experience has demonstrated that the process of adipocyte dedifferentiation is quite independent from cell donor characteristics including disease state, which considerably decreases its appeal as a health-related parameter. Our program’s Long-term Objective is two-fold: 1) to develop and refine culture techniques that may be of use to study the biological nature of adipocytes; and 2) to generate a body of knowledge on dedifferentiated adipocytes that will help other investigators move dedifferentiated cells into the sphere of tissue engineering.