Bosse A, Wulf M, Wiethege T, Voss B, Müller K M
Institut für Pathologie, Berufsgenossenschaftliche Kliniken Bergmannsheil, Universitätsklinik, Bochum.
Pathologe. 1994 Aug;15(4):216-25. doi: 10.1007/s002920050048.
Heterotopic Ossification (HO) occurs as a consequence of several diseases and of various forms of trauma. HO is particularly frequent in paraplegic patients with spinal cord lesions. It is obvious that extraskeletal cells are able to differentiate into an osteogenic direction. However, the mechanisms of the induction process of HO and the stimulating agents are not precisely known. A novel tool for studying the ossification process at the level of transcription is the technique of non-radioactive in situ hybridisation. Using digoxigenin labeled cDNA probes we investigated the distribution patterns of types I, II and III collagen mRNAs and the mRNA of Transforming Growth Factor beta 1 (TGF-beta 1) in heterotopic ossification of pressure sores of paraplegic patients. The three collagen mRNAs as well as the TGF-beta 1 mRNA exhibited substantially divergent distribution patterns. Type I (alpha 1) collagen mRNA was predominantly detectable in preosteoblasts, chondroblasts and chondrocytes of the ossification zone. Type II (alpha 1) collagen mRNA was nearly exclusively found in cells of the chondrogenic lineage. Type III (alpha 1) collagen mRNA was detectable at low levels in soft tissue, but was strongly expressed by chondroblasts and chondrocytes of heterotopic cartilage. In contrast expression of TGF-beta 1 mRNA was found in a spatial different distribution pattern in areas of proliferation of mesenchymal tissue and in different stages of ectopic bone formation. As in the case of collagen Type I (alpha 1) and III (alpha 1) mRNAs the maximum of localization of TGF-beta 1 was detected in chondroblastic areas of heterotopic ossification. Taken together our in situ hybridization experiments provide evidence that chondrogenic cells play a central role in the process of HO with a phenotypic alteration in collagen type expression and a strong expression of TGF-beta 1 mRNA. These findings support individual in vivo function for TGF-beta 1 in local cellular regulation of ectopic bone formation.
异位骨化（HO）是多种疾病及各种创伤形式导致的结果。HO在脊髓损伤的截瘫患者中尤为常见。显然，骨骼外细胞能够向成骨方向分化。然而，HO诱导过程的机制以及刺激因子尚不完全清楚。非放射性原位杂交技术是一种在转录水平研究骨化过程的新工具。我们使用地高辛标记的cDNA探针，研究了截瘫患者压疮异位骨化中I型、II型和III型胶原蛋白mRNA以及转化生长因子β1（TGF-β1）mRNA的分布模式。三种胶原蛋白mRNA以及TGF-β1 mRNA呈现出显著不同的分布模式。I型（α1）胶原蛋白mRNA主要在骨化区的前成骨细胞、成软骨细胞和软骨细胞中检测到。II型（α1）胶原蛋白mRNA几乎仅在软骨形成谱系的细胞中发现。III型（α1）胶原蛋白mRNA在软组织中低水平可检测到，但在异位软骨的成软骨细胞和软骨细胞中强烈表达。相比之下，TGF-β1 mRNA在间充质组织增殖区域和异位骨形成的不同阶段呈现出空间上不同的分布模式。与I型（α1）和III型（α1）胶原蛋白mRNA的情况一样，TGF-β1定位的最大值在异位骨化的成软骨细胞区域检测到。综上所述，我们的原位杂交实验提供了证据，表明软骨形成细胞在HO过程中起核心作用，伴随着胶原蛋白类型表达的表型改变以及TGF-β1 mRNA的强烈表达。这些发现支持了TGF-β1在异位骨形成的局部细胞调节中的个体体内功能。
