Osinga Rik, Di Maggio Nunzia, Todorov Atanas, Allafi Nima, Barbero Andrea, Laurent Frédéric, Schaefer Dirk Johannes, Martin Ivan, Scherberich Arnaud
Department of Plastic, Reconstructive, Aesthetic, and Hand Surgery, University Hospital of Basel, Basel, Switzerland Laboratory of Tissue Engineering, Department of Surgery, University Hospital of Basel, Basel, Switzerland Department of Biomedicine, University of Basel, Basel, Switzerland.
Laboratory of Tissue Engineering, Department of Surgery, University Hospital of Basel, Basel, Switzerland Department of Biomedicine, University of Basel, Basel, Switzerland.
Stem Cells Transl Med. 2016 Aug;5(8):1090-7. doi: 10.5966/sctm.2015-0256. Epub 2016 Jun 22.
: Recapitulation of endochondral ossification (ECO) (i.e., generation of marrow-containing ossicles through a cartilage intermediate) has relevance to develop human organotypic models for bone or hematopoietic cells and to engineer grafts for bone regeneration. Unlike bone marrow-derived stromal cells (also known as bone marrow-derived mesenchymal stromal/stem cells), adipose-derived stromal cells (ASC) have so far failed to form a bone organ by ECO. The goal of the present study was to assess whether priming human ASC to a defined stage of chondrogenesis in vitro allows their autonomous ECO upon ectopic implantation. ASC were cultured either as micromass pellets or into collagen sponges in chondrogenic medium containing transforming growth factor-β3 and bone morphogenetic protein-6 for 4 weeks (early hypertrophic templates) or for two additional weeks in medium supplemented with β-glycerophosphate, l-thyroxin, and interleukin1-β to induce hypertrophic maturation (late hypertrophic templates). Constructs were implanted in vivo and analyzed after 8 weeks. In vitro, ASC deposited cartilaginous matrix positive for glycosaminoglycans, type II collagen, and Indian hedgehog. Hypertrophic maturation induced upregulation of type X collagen, bone sialoprotein, and matrix metalloproteinase13 (MMP13). In vivo, both early and late hypertrophic templates underwent cartilage remodeling, as assessed by MMP13- and tartrate-resistant acid phosphatase-positive staining, and developed bone ossicles, including bone marrow elements, although to variable degrees of efficiency. In situ hybridization for human-specific sequences and staining with a human specific anti-CD146 antibody demonstrated the direct contribution of ASC to bone and stromal tissue formation. In conclusion, despite their debated skeletal progenitor nature, human ASC can generate bone organs through ECO when suitably primed in vitro.
Recapitulation of endochondral ossification (ECO) (i.e., generation of marrow-containing ossicles through a cartilage intermediate) has relevance to develop human organotypic models for bone or hematopoietic cells and to engineer grafts for bone regeneration. This study demonstrated that expanded, human adult adipose-derived stromal cells can generate ectopic bone through ECO, as previously reported for bone marrow stromal cells. This system can be used as a model in a variety of settings for mimicking ECO during development, physiology, or pathology (e.g., to investigate the role of BMPs, their receptors, and signaling pathways). The findings have also translational relevance in the field of bone regeneration, which, despite several advances in the domains of materials and surgical techniques, still faces various limitations before being introduced in the routine clinical practice.
软骨内成骨（ECO）的重现（即通过软骨中间体生成含骨髓的小骨）与开发用于骨或造血细胞的人体器官型模型以及设计用于骨再生的移植物相关。与骨髓来源的基质细胞（也称为骨髓来源的间充质基质/干细胞）不同，脂肪来源的基质细胞（ASC）迄今为止未能通过ECO形成骨器官。本研究的目的是评估在体外将人ASC诱导至软骨形成的特定阶段是否能使其在异位植入后自主进行ECO。ASC以微团颗粒形式培养或接种到含有转化生长因子-β3和骨形态发生蛋白-6的软骨形成培养基中的胶原海绵中，培养4周（早期肥大模板），或在补充有β-甘油磷酸、L-甲状腺素和白细胞介素1-β的培养基中再培养两周以诱导肥大成熟（晚期肥大模板）。构建体植入体内，8周后进行分析。在体外，ASC沉积了对糖胺聚糖、II型胶原和印度刺猬蛋白呈阳性的软骨基质。肥大成熟诱导了X型胶原、骨唾液蛋白和基质金属蛋白酶13（MMP13）的上调。在体内，通过MMP13和抗酒石酸酸性磷酸酶阳性染色评估，早期和晚期肥大模板均经历了软骨重塑，并形成了包括骨髓成分在内的骨小骨，尽管效率程度不同。针对人特异性序列的原位杂交和用人特异性抗CD146抗体染色证明了ASC对骨和基质组织形成的直接贡献。总之，尽管人ASC的骨骼祖细胞性质存在争议，但在体外适当诱导时，它们可以通过ECO生成骨器官。
软骨内成骨（ECO）的重现（即通过软骨中间体生成含骨髓的小骨）与开发用于骨或造血细胞的人体器官型模型以及设计用于骨再生的移植物相关。本研究表明，如先前报道的骨髓基质细胞一样，扩增的成人脂肪来源的基质细胞可以通过ECO生成异位骨。该系统可在各种情况下用作模型，以模拟发育、生理或病理过程中的ECO（例如，研究骨形态发生蛋白、其受体和信号通路的作用）。这些发现在骨再生领域也具有转化相关性，尽管材料和手术技术领域取得了一些进展，但在引入常规临床实践之前，骨再生仍面临各种限制。
