Transcription profiling of rat to study the effect of hindlimb unloading on healing of medial collateral ligaments 3 weeks after injury

A recent physiological study established that hindlimb unloading of rats at 3 and 7 weeks inhibits healing of injured ligaments resulting in a badly aligned discontinuous collagen matrix. Using tissue from these rats we focused on the 3-week time point employing microarray analysis to identify what cellular processes or lack of processes could account for these observed deficiencies. We used the Affymetrix RG_U34A GeneChip and performed image analysis with Microarray Suite 5.0. For normalization we used the MAS global normalization protocol with a default target mean signal of 500. Gene expression in medial collateral ligament tissue under 4 different treatment conditions was measured: loaded control loaded wound healing unloaded control and unloaded wound healing. From our results it appears that unloaded tissue lags behind loaded tissue in its progression through the healing process and at 3 weeks is still engaged in the proliferative phase whereas loaded tissue is actively remodeling its collagen matrix.

近期一项生理学研究表明，对大鼠进行3周和7周的远端肢体卸载会抑制受损韧带的愈合，导致胶原基质严重错位且连续性中断。利用这些大鼠的组织，本研究聚焦于3周的时间点，通过微阵列分析识别可能解释这些观察到的缺陷的细胞过程或过程缺乏。本研究采用了Affymetrix RG_U34A基因芯片，并使用Microarray Suite 5.0进行图像分析。在标准化处理中，采用了MAS全局标准化方案，目标平均信号强度设定为500。对内侧副韧带组织在四种不同治疗条件下的基因表达进行了测量：负重对照组、负重创伤愈合组、非负重对照组以及非负重创伤愈合组。根据我们的研究结果，非负重组织在愈合过程中的进展落后于负重组织，且在3周时仍处于增殖阶段，而负重组织则正在积极重塑其胶原基质。