Manipulating chondrogenic progenitor cells in osteoarthritis for cartilage repair in humans

在骨关节炎(OA)中，病变的透明软骨组织的再生仍然是一个巨大的挑战，因为退变优先于组织的自我更新能力。最近，我们发现了多能细胞、克隆细胞和迁移细胞，它们存在于晚期骨性关节炎的修复组织中。这些软骨生成前体细胞(CPC)在人骨关节炎软骨组织中的成软骨潜能是由抑制转录因子Runx2和Sox9控制的(Koling等。2009年，细胞干细胞)。下调Runx2可增强Sox9的表达，从而促进透明基质分子的产生。由于它们的广泛作用，直接操纵这些关键角色作为一种治疗方法是不可行的。因此，我们阐明了Runx2和Sox9的共同调节因子--例如RAB5C、YWHAE、DDX5、LEMD2--上调Sox9，下调Runx2。我们的目标是过表达并下调(CRISPAR/Cas9)这些共同调节因子，以促进人CPC的软骨形成。为了为它们在小鼠模型中的应用铺平道路，这些共调节因子的小鼠同源物将应用于来自OA小鼠模型(BMP2-Gdf5cKO)的小鼠CPC。在小鼠和人CPC中增强Sox9和降低Runx2的共调节基因将被转染到小鼠CPC中，并被植入裸鼠体内的水凝胶中。这一活体小鼠实验将阐明原位操纵的CPC的软骨形成潜力。这一结果将有助于以更微调的方式操纵CPC向软骨形成方向发展，为骨性关节炎的细胞生物学治疗开辟新的途径，以修复软骨和推迟全膝关节置换。

Regeneration of diseased hyaline cartilage tissue in osteoarthritis (OA) continues to be a great challenge because degeneration overrides the tissue self-renewal capacity. Recently, we identified multipotent, clonogenic and migratory cells, which are present in the repair tissue of late stages of OA. The chondrogenic potential of these chondrogenic progenitor cells (CPCs) in human OA cartilage tissue is controlled by the counteracting transcription factors runx2 and sox9 (Koelling et al. 2009, Cell Stem Cell). Down-regulation of runx2 enhances sox9 expression and thereby the production of hyaline matrix molecules. Direct manipulation of these essential players is not feasible as a therapeutic approach due to their broad actions. Therefore, we have elucidated co-regulators of runx2 and sox9 -for example, RAB5C, YWHAE, DDX5, LEMD2- that up-regulate sox9 and down-regulate runx2. We aim to overexpress and knock-down (CRISPAR/Cas9) these co-regulators to enhance chondrogenesis in human CPCs. To pave the way for their use in a mouse model, the mouse homologues of these co-regulators will be applied in mouse CPCs from an OA mouse model (BMP2-Gdf5cKO). Co-regulators enhancing sox9 and reducing runx2 in mouse and human CPC will be transfected in mouse CPCs and embedded in a hydrogel implanted in nude mice. This in vivo mouse experiment will elucidate the chondrogenic potential of manipulated CPCs in situ. The results will help to manipulate CPCs towards chondrogenesis in a more fine-tuned way to open new avenues for the cell biological treatment of OA to repair cartilage and postpone total knee replacement.