Martinez D A, Vailas A C, Vanderby R, Grindeland R E
Connective Tissue Physiology Laboratory, Department of Health and Human Performance, Univ. of Houston, N207 D Engineering Bldg. 1, Houston, TX 77204-4006, USA.
Am J Physiol Regul Integr Comp Physiol. 2007 Oct;293(4):R1552-60. doi: 10.1152/ajpregu.00423.2007. Epub 2007 Aug 15.
Previous data from spaceflight studies indicate that injured muscle and bone heal slowly and abnormally compared with ground controls, strongly suggesting that ligaments or tendons may not repair optimally as well. Thus the objective of this study was to investigate the biochemical and molecular gene expression of the collagen extracellular matrix in response to medial collateral ligament (MCL) injury repair in hindlimb unloaded (HLU) rodents. Male rats were assigned to 3- and 7-wk treatment groups with three subgroups each: sham control, ambulatory healing (Amb-healing), and HLU-healing groups. Amb- and HLU-healing animals underwent bilateral surgical transection of their MCLs, whereas control animals were subjected to sham surgeries. All surgeries were performed under isoflurane anesthesia. After 3 wk or 7 wk of HLU, rats were euthanized and MCLs were surgically isolated and prepared for molecular or biochemical analyses. Hydroxyproline concentration and hydroxylysylpyridinoline collagen cross-link contents were measured by HPLC and showed a substantial decrement in surgical groups. MCL tissue cellularity, quantified by DNA content, remained significantly elevated in all HLU-healing groups vs. Amb-healing groups. MCL gene expression of collagen type I, collagen type III, collagen type V, fibronectin, decorin, biglycan, lysyl oxidase, matrix metalloproteinase-2, and tissue inhibitor of matrix metalloproteinase-1, measured by real-time quantitative PCR, demonstrated differential expression in the HLU-healing groups compared with Amb-healing groups at both the 3- and 7-wk time points. Together, these data suggest that HLU affects dense fibrous connective tissue wound healing and confirms previous morphological and biomechanical data that HLU inhibits the ligament repair processes.
以往太空飞行研究的数据表明，与地面对照组相比，受伤的肌肉和骨骼愈合缓慢且异常，这强烈表明韧带或肌腱可能也无法实现最佳修复。因此，本研究的目的是调查后肢卸载（HLU）啮齿动物内侧副韧带（MCL）损伤修复过程中胶原细胞外基质的生化和分子基因表达。将雄性大鼠分为3周和7周治疗组，每组再分为三个亚组：假手术对照组、自主活动愈合（Amb-愈合）组和HLU-愈合组。Amb-愈合组和HLU-愈合组动物均接受双侧MCL手术横断，而对照组动物接受假手术。所有手术均在异氟烷麻醉下进行。HLU处理3周或7周后，对大鼠实施安乐死，手术分离MCL并准备进行分子或生化分析。通过高效液相色谱法测量羟脯氨酸浓度和羟赖氨酰吡啶啉胶原交联含量，结果显示手术组显著降低。通过DNA含量定量的MCL组织细胞密度在所有HLU-愈合组中仍显著高于Amb-愈合组。通过实时定量PCR测量MCL中I型胶原、III型胶原、V型胶原、纤连蛋白、核心蛋白聚糖、双糖链蛋白聚糖、赖氨酰氧化酶、基质金属蛋白酶-2和基质金属蛋白酶组织抑制剂-1的基因表达，结果表明在3周和7周时间点，HLU-愈合组与Amb-愈合组相比均存在差异表达。这些数据共同表明，HLU会影响致密纤维结缔组织伤口愈合，并证实了之前关于HLU抑制韧带修复过程的形态学和生物力学数据。
