Orthopaedic Research Laboratory, Department of Orthopaedics, Erasmus MC, Room Ee1614, PO Box 2040, 3000CA Rotterdam, The
Eur Cell Mater. 2014 Feb 19;27:137-48; discussion 148. doi: 10.22203/ecm.v027a11.
Grafting bone defects or atrophic non-unions with mesenchymal stromal cells (MSCs)-based grafts is not yet successful. MSC-based grafts typically use undifferentiated or osteogenically differentiated MSCs and regenerate bone through intramembranous ossification. Endochondral ossification might be more potent but requires chondrogenic differentiation of MSCs. Here, we determined if chondrogenically differentiated MSC (ch-MSC) pellets could induce bone regeneration in an orthotopic environment through endochondral ossification. Undifferentiated MSC pellets (ud-MSC) and ch-MSC pellets were generated from MSCs of human donors cultured on chondrogenic medium for respectively 3 (ud-MSC) and 21 (ch-MSC) days. A 6 mm femoral bone defect was made and stabilised with an internal plate in 27 athymic rats. Defects were left empty for 6 weeks to develop an atrophic non-union before they were grafted with ch-MSC pellets or ud-MSC pellets. Micro-CT scans made 4 and 8 weeks after grafting showed that ch-MSC pellets resulted in significantly more bone than ud-MSC pellets. This regenerated bone could completely bridge the defect, but the amount of bone regeneration was donor-dependent. Histology after 7 and 14 days showed slowly mineralising pellets containing hypertrophic chondrocytes, as well as TRAP-positive and CD34-positive cells around the ch-MSC pellets, indicating osteoclastic resorption and vascularisation typical for endochondral ossification. In conclusion, grafting critical femoral bone defects with chondrogenically differentiated MSC pellets led to rapid and pronounced bone regeneration through endochondral ossification and may therefore be a more successful MSC-based graft to repair large bone defects or atrophic non-unions. But, since bone regeneration was donor-depend, the generation of potent chondrogenically differentiated MSC pellets for each single donor needs to be established first.
用间充质基质细胞（MSCs）为基础的移植物来移植骨缺损或萎缩性骨不连尚未成功。MSCs 为基础的移植物通常使用未分化或成骨分化的 MSCs，并通过膜内成骨来再生骨。软骨内成骨可能更有效，但需要 MSCs 的软骨分化。在这里，我们确定了软骨分化的 MSC（ch-MSC）球体是否可以通过软骨内成骨在原位环境中诱导骨再生。未分化的 MSC 球体（ud-MSC）和 ch-MSC 球体分别由在软骨形成培养基中培养的人供体 MSC 生成 3（ud-MSC）和 21（ch-MSC）天。在 27 只无胸腺大鼠中，通过内置板制作了一个 6mm 的股骨骨缺损，并使其稳定。在移植 ch-MSC 球体或 ud-MSC 球体之前，让缺陷处空出 6 周以形成萎缩性骨不连。在移植后 4 和 8 周进行微 CT 扫描显示，ch-MSC 球体导致的骨量明显多于 ud-MSC 球体。这种再生的骨可以完全桥接缺损，但骨再生的量取决于供体。移植后 7 和 14 天的组织学显示，缓慢矿化的球体含有肥大的软骨细胞，以及 ch-MSC 球体周围的 TRAP 阳性和 CD34 阳性细胞，表明存在典型的软骨内成骨的破骨细胞吸收和血管化。总之，用软骨分化的 MSC 球体移植临界股骨骨缺损可通过软骨内成骨导致快速和明显的骨再生，因此可能是一种更成功的基于 MSC 的移植物，可用于修复大的骨缺损或萎缩性骨不连。但是，由于骨再生取决于供体，因此需要首先为每个供体建立有效的软骨分化的 MSC 球体生成方法。
