CELL-DERIVED EXTRACELLULAR MATRIX TAILORING FOR INTERVERTEBRAL DISC REGENERATION

Abstract

Intervertebral disc (IVD) degeneration is characterized by tissue loss of function and major structural changes, which can lead to Low Back Pain. Current treatments fail to tackle the disc's hindered function and degenerative alterations. Our goal is to promote IVD regeneration, through the recapitulation of a fetal-like microenvironment based on a tailored cell-derived matrix (CDM), rich in two fetal exclusive collagens – COLXII and COLXIV. We hypothesize that this engineered CDM will have a pro-regenerative potential and allow IVD functional restoration. Immortalized mesenchymal stromal/stem cells (iMSCs) were transduced with the CRISPR/dCas9-VP64 lentiviral system, targeting COL12A1 or COL14A1. Gene and protein expression were evaluated by qRT-PCR, Western Blot and immunofluorescence. Simultaneously, optimization of CDM decellularization protocol was performed. Process efficacy was validated by immunofluorescence. DNA content was quantified using the Quant-iT™ PicoGreen™ Kit. Successful iMSCs engineering was confirmed by an average increase of mRNA relative expression for both collagens (2.12-fold for COL12A1 and 11.7-fold for COL14A1). Protein level assessment by western blot and immunofluorescence confirmed increased COLXII and COLXIV. Decellularized CDM production was optimized. Cell removal was demonstrated by nuclear and actin staining reduction, when compared with the non-decellularized control. DNA content showed a marked decrease in both NH4OH- and SDS-based protocols. Matrix preservation after decellularization was confirmed by fibronectin staining only in the NH4OH-based decellularization. Preliminary proteomic characterization data of engineered iMSCs as shown some functional impact namely on Sonic Hedgehog (Shh) pathway and repression of pain by DREAM (Downstream regulator element antagonist modulator). In conclusion, we were able to establish a CRISPR activating system for COL12A1 and COL14A1, allowing the use of iMSCs as biofactories for a IVD fetal-tailored CDM. The use of a customized ECM and fetal microenvironment recapitulations is an innovative strategy for IVD functional restoration, and its versatility opens new avenues in the tissue regeneration field.