Degradation of human hair keratin scaffold implanted for repairing injured skeletal muscles.
OBJECTIVE
To observe the in vivo degradation process of human hair keratin (HHK) scaffold after implantation in rabbits.


METHODS
Seven New Zealand rabbits were divided into 4 groups including a control group and 3 operation groups. HHK scaffold was implanted, after partial resection of the skeletal muscles, in rabbits of the 3 operation groups, followed by observation 1, 3, and 6 weeks later respectively. Routine morphological observation, histochemistry with ubiquitin and electron microscopy were performed. HHK scaffold incorporated 3 types of HHK with different degradation speeds, respectively designated types F, B, and Z.


RESULTS
Light microscopic observation revealed that human hair cuticles began to strip off at the first postoperative week, and the material was homogeneous on the surface of which macrophagocytes and multinuclear giant cells adhered. At the third week HHK scaffold was degraded into particles as seen under electron microscope and was phagocytosed by macrophagocytes and multinuclear giant cells. Ubiquitin enzymatic histochemistry demonstrated that macrophagocytes, multinuclear giant cells were positive at the first week. At sixth week, further degradation of HHK scaffold occurred when newly generated muscles were seen beside the HHK.


CONCLUSIONS
HHK scaffold is initially degraded extracellularly by ubiquitin system into particles, which are phagocytosed by the cells and degraded by the cooperation of lysosome and ubiquitin; meanwhile the satellite cells are activated, beginning to proliferate and eventually fused into newly generated muscle fibers.
Qiao
Dong-Fang
DF
Central Laboratory, First Military Medical University, Guangzhou 510515, China.
Lu
Yan-Meng
YM
Fu
Wen-Yu
WY
Piao
Ying-Jie
YJ
D000818:Animals; D006197:Hair / Q000378:metabolism*; D006801:Humans; D007124:Immunoenzyme Techniques; D007633:Keratins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000293:injuries*; D011817:Rabbits
D007633:Keratins