A Synthetic Receptor Platform to Engineer Mesenchymal Stromal Cells for Osteoarthritis Detection and Guided Articular Cartilage Regenerative Medicine
Abstract
Osteoarthritis (OA) treatment remains a significant clinical challenge due to the absence of disease-modifying therapies. Current approaches are primarily palliative, providing symptom relief or temporary efficacy without addressing the underlying pathology, including the degradation of articular cartilage. Mesenchymal stromal cells (MSCs) have shown promise for cartilage repair, but their therapeutic effects remain inconsistent and insufficiently targeted to OA pathology, limiting their clinical utility. To address these shortcomings, we engineered a synthetic Notch (synNotch) receptor that allows precise, spatially controlled activation of MSCs in response to type II collagen (CII), an extracellular matrix component exposed during OA-associated cartilage degradation. This system enables receptor activation and transgene expression only upon direct engagement with CII-coated substrates, including both adsorbed CII and enzymatically degraded, primary cartilage tissue. Notably, engineered CII-synNotch MSCs produce supraphysiologic levels of pro-anabolic transforming growth factor-beta 3 (TGF-β3) and anti-catabolic interleukin-1 receptor antagonist (IL-1Ra), two key modulators of OA pathology. Sustained transgene production facilitated both anabolic gene expression of MSCs and modulation of IL-1-associated inflammation in chondrocyte co-cultures. However, in vivo, CII-synNotch cells exhibited ligand-independent activation, prompting further investigation into underlying proteolytic and mechanical mechanisms of receptor activation in the joint. We investigated receptor-mediated activation in arthritic joints using canonical synNotch receptors and alternative receptor designs. While these studies offered insights into factors contributing to off-target activation, further optimization is required to enhance receptor specificity and achieve controlled activation that is aligned with OA progression. The findings presented here establish a foundation for synthetically regulated, engineered cell therapies that respond to OA-specific pathological features for programmed therapeutic effects.
Description
Keywords
Osteoarthritis, Synthetic Notch, Mesenchymal Stromal Cells