Mizuta H, Kudo S, Nakamura E, Takagi K, Hiraki Y
Department of Orthopaedic and Neuro-Musculoskeletal Surgery, Faculty of Medical and Pharmaceutical Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
Osteoarthritis Cartilage. 2006 Sep;14(9):944-52. doi: 10.1016/j.joca.2006.03.009. Epub 2006 Apr 27.
We studied the accumulation of parathyroid hormone (PTH)/PTHrP receptor-positive mesenchymal cells using double immunohistochemistry and examined whether this correlated with the subsequent regeneration of 3-mm-diameter full-thickness defects of articular cartilage.
Cylindrical full-thickness articular cartilage defects (3 mm) were artificially created in the femoral trochlea of male adolescent Japanese white rabbits (n = 210) with a hand-drill. Recombinant human PTH(1-84) was then administered into the defect cavities with an osmotic pump for either 2 or 4 weeks post-injury. Following PTH treatment, the repair processes in the cartilage defects were histologically examined. Double immunostaining analyses for the PTH/PTH-related peptide (PTHrP) receptor and proliferating cell nuclear antigen (PCNA) in the regenerating tissues were then performed.
Activation of PTH/PTHrP receptor signaling by hPTH(1-84) results in the inhibition of chondrogenic differentiation in full-thickness articular cartilage defects. At the conclusion of the 2-week PTH treatment, the defect cavities were filled with undifferentiated mesenchymal cells, which were similar to the controls. In addition, almost all of these cells localized at the center of the injuries were both PTH/PTHrP receptor- and PCNA-positive. In contrast, after prolonged PTH treatment for 4 weeks, there was no indication of a cartilaginous repair response and cells that had migrated to the defect cavities were found to have irreversibly lost expression of the PTH/PTHrP receptor.
The chondrogenic capacity of cells that had migrated to the area of these defect cavities is closely associated with their ability to express the PTH/PTHrP receptor. Moreover, these cells maintain their chondrogenic potential within only a limited time-span of 2 weeks.
我们使用双重免疫组织化学研究甲状旁腺激素（PTH）/PTHrP受体阳性间充质细胞的积累，并检查这是否与随后直径3毫米的关节软骨全层缺损的再生相关。
用手钻在雄性青春期日本白兔（n = 210）的股骨滑车中人为制造圆柱形全层关节软骨缺损（3毫米）。然后在损伤后2周或4周，用渗透泵将重组人PTH(1 - 84)注入缺损腔。PTH治疗后，对软骨缺损处的修复过程进行组织学检查。然后对再生组织中的PTH/PTH相关肽（PTHrP）受体和增殖细胞核抗原（PCNA）进行双重免疫染色分析。
hPTH(1 - 84)激活PTH/PTHrP受体信号传导会抑制全层关节软骨缺损中的软骨形成分化。在2周PTH治疗结束时，缺损腔充满了未分化的间充质细胞，与对照组相似。此外，几乎所有位于损伤中心的这些细胞均为PTH/PTHrP受体和PCNA阳性。相反，在延长PTH治疗4周后，没有软骨修复反应的迹象，并且发现迁移到缺损腔的细胞已不可逆地失去PTH/PTHrP受体的表达。
迁移到这些缺损腔区域的细胞的软骨形成能力与其表达PTH/PTHrP受体的能力密切相关。此外，这些细胞仅在有限的2周时间内维持其软骨形成潜能。
