Boswell C A, Williams S K
Department of Surgery, Arizona Health Sciences Center, Tucson 85724-5084, USA.
J Biomater Sci Polym Ed. 1999;10(3):319-29. doi: 10.1163/156856299x00388.
Expanded polytetrafluoroethylene (ePTFE) implants are being increasingly used as vascular prostheses and other devices. However the tissue response associated with this and other polymer implants continues to limit any long-term function. One of the major approaches currently being investigated to improve biocompatibility involves surface modification of the base polymer. In this report, we attempted to alter the healing characteristics of ePTFE by denucleation, a process which removes air trapped within the interstices of the material. Additionally, adsorption of extracellular proteins on the denucleated polymer was also tested. After 5 weeks implanted in subcutaneous and epididymal fat sites of rats, the material was explanted and the healing around the implant evaluated histologically. We found that in skin implants, denucleation alone resulted in a substantial reduction in the fibrous capsule which has been previously reported for untreated ePTFE, and an increase in blood vessel development around and within the polymer. Absorption of extracellular matrix proteins prior to implantation resulted in a reduced vascularity of the implants compared with denucleation-only implants. Implants in fat tissue, regardless of treatment, showed very little tissue reaction, either in the number of inflammatory cells, development of a fibrous capsule or neovascularization. These results suggest that the presence of air nuclei within porous material may contribute to the inappropriate healing response associated with these polymers. In addition, they confirm earlier reports that healing around implanted polymers is tissue-specific.
膨体聚四氟乙烯（ePTFE）植入物正越来越多地被用作血管假体和其他装置。然而，与这种及其他聚合物植入物相关的组织反应持续限制其任何长期功能。目前为改善生物相容性而正在研究的主要方法之一涉及对基础聚合物进行表面改性。在本报告中，我们试图通过去核处理来改变ePTFE的愈合特性，去核是一种去除材料孔隙中 trapped air的过程。此外，还测试了细胞外蛋白质在去核聚合物上的吸附情况。将材料植入大鼠皮下和附睾脂肪部位5周后，取出植入物并通过组织学方法评估植入物周围的愈合情况。我们发现，在皮肤植入物中，仅去核处理就导致先前报道的未处理ePTFE的纤维囊大幅减少，并且聚合物周围和内部的血管生成增加。与仅去核处理的植入物相比，植入前吸收细胞外基质蛋白导致植入物的血管化程度降低。脂肪组织中的植入物，无论经过何种处理，在炎症细胞数量、纤维囊形成或新血管生成方面均显示出极少的组织反应。这些结果表明，多孔材料中空气核的存在可能导致与这些聚合物相关的不适当愈合反应。此外，它们证实了早期的报道，即植入聚合物周围的愈合具有组织特异性。
