鸡羽根管作为组织工程支架材料的初步研究

目的 了解鸡羽根的结构特点,观察其在活体组织内的降解情况及其对周围组织的影响,为其作为组织工程备选支架材料提供依据.方法 健康鸡羽根,采用序贯的、不同程度(轻、中、重)理化处理程序,得到3种鸡羽根角蛋白(CCK-Ⅰ、CCK-Ⅱ、CCK-Ⅲ),光学显微镜/扫描电镜观察其形态结构.大鼠背部肌组织内植入鸡羽根角蛋白片(实验组)和未处理鸡羽根片(对照组),以及坐骨神经束间植入鸡羽根角蛋白丝(实验组)和未处理羽根丝(对照组),于不同时间点取材,观察其降解情况和组织相容性.结果 (1)光镜:鸡羽根管壁从内到外依次为4个致密层:嗜碱性均质状粗线,3～5层的嗜酸性角质层,60～100层含大量色素颗粒的环行角蛋白束和10～20层含少量色素颗粒的角蛋白束.扫描电镜:未处理的鸡羽根结构致密,管壁平整,无孔洞;处理后结构较疏松,可见大小、深浅不等的孔洞.(2)肌组织内植入:第8周材料呈细丝状或散在细颗粒状,部分被降解吸收,仍有少量炎性细胞,可见多核巨细胞;第12周材料降解为细小碎片.对照组各时间段材料结构完整.(3)神经束间植入:引起的组织反应与细胞类型同肌组织内植入组,神经组织无变性、坏死.结论 未处理的鸡羽根由多层致密的角蛋白束构成,含色素颗粒和少量基质.处理后表面出现许多孔洞,结构疏松,且体内可降解,其降解产物不引起机体组织的变性、坏死.鸡羽根有可能成为组织工程化器官或组织构建的备用支架材料.

Preliminary study of chicken calamus conduit as a scaffold material for tissue engineering

Objective To observe the unique structural features of chicken calamus keratin (CCK) conduit as a candidate scaffold material for tissue engineering and its in vivo degradation and histocompatibility after its implantation into living tissues. Methods Chicken calami were taken from healthy chickens and treated through sequential, controllable physical and biochemical procedures for preparation of three types of CCK conduits, namely CCK-I (mildly treated), CCK-II (moderately treated) and CCK-III (intensely treated). Light microscopy (LM) and scanning electron microscopy (SEM) were performed for morphological observation. Each of these three types of CCK pieces (experimental group) and the untreated ones (control group) was implanted into the dorsal muscular tissue on both sides of SD rats, respectively. Routine tissue sectioning and HE stain were performed to identify the morphological changes under light microscope. Each of the CCK threads (experimental group) and the untreated chicken calamus threads (control group) was also grafted within the sciatic nerve bundles of SD rats, respectively. Results The wall of the chicken calamus was composed of 4 compact parts from inside to outside on cross sections, namely the innermost basophilic homogenous coarse line, 3-5 layers of acidophilic corneum, 60-100 layers of circular keratin tracts containing massive pigment granules, and 10-20 outmost layers of keratin tracts with only a few pigment granules. The three-dimensional surface features of chicken calamus identified by SEM, as compared with untreated chicken calamus, was characterized by loose arrangement containing horizontal and vertical keratins with obvious pores of different sizes and depths on its surface. At 8 weeks after implantation into the muscular tissue in experimental groups, the CCK grafts were degraded into thin filaments or/and dispersed pieces and fine granules with the appearance of blood vessels, which facilitated the absorption of the degradation products; at 12 weeks, the grafts were markedly degraded into tiny fragments. In the control group, in contrast, the grafts remains intact throughout the experiment. After implantation of the material into the nerve bundles, similar cell infiltration and tissue responses to the grafts were observed as compared to those occur in intramuscular grafting. The degradation products did not seem to cause nerve tissue degeneration or necrosis. Conclusions Fresh chicken calamus is a natural tube composed of multi-layered compact keratin tracts with pigment granules and small amount of matrix, and is non-absorbable in vivo, and therefore does not favor the purpose for use directly as a candidate biological scaffold. After proper treatment, the chicken calamus becomes loosely arranged porous material, and can be degraded and absorbed in vivo without resulting in tissue degradation or necrosis, suggesting its potential for applications in tissue engineering.