製備刺激血管新生之複合材料做為可注射式骨泥治療股骨頭缺血性壞死之研究

Abstract

股骨頭缺血性壞死是常見的骨疾之一，一般早期的治療手術是核心減壓，但是病人在經此手術後，股骨頭無法馬上得到機械強度上的支撐，必須避免讓股骨頭承受壓力，因此患者的生活受到很大的限制，造成極大的不便。我們希望發展生物可分解及促進血管新生的骨泥，於病人核心減壓後注入，初期提供機械強度及幫助血管新生提供營養，以促進骨組織復原，期望新的骨組織能取代分解掉的骨泥，使患部復原。 聚富馬酸丙二醇酯即聚丙烯延胡索酸酯(poly(propylene fumarate)；PPF)是一種聚合溫度低，且具有生物可分解性的高分子材料，加上生物可吸收性另又具有骨誘導性的磷酸鈣鹽水泥，以增加機械強度，再配合有促進血管新生功能的人蔘萃取物：人蔘皂苷Rg1。以此複合材料希望能在給予病人股骨頭機械強度支持時，亦能促進股骨頭血管再生進入患部取代生物可分解之骨泥。 本實驗主要架構前半部在探討磷酸鈣鹽於聚富馬酸丙二醇酯系統中不同比例，骨泥對細胞相容性、骨泥強度、聚合溫度、腫脹測試的影響，實驗結果顯示，增加磷酸鈣鹽於聚富馬酸丙二醇酯中的比例，對於增加細胞相容性有顯著的影響，也對增加骨泥強度，減少聚合溫度，減少腫脹有顯著的影響。後半部我們選取了較佳的磷酸鈣鹽和聚富馬酸丙二醇酯的比例並加入不同量的刺激血管新生劑Rg1，分析其藥物釋放行為，並確定釋放之Rg1 仍維持藥性，由實驗數據知，不論Rg1 的比例為多少，皆有幾近相同的累積釋放模式，我們選擇較適當的藥量，以萃取液用人類臍帶靜脈內皮細胞在培養盤做管狀形成(tube formation)測試，顯示骨泥中釋放之Rg1 仍然維持刺激血管形成之藥效。由上述試驗可知，此種可注射式、生物可分解、又具有刺激血管增生能力的骨泥，極具發展潛力應用在缺血性股骨頭壞死治療，以造福遭受痛苦的病患。

Avascular necrosis of the femoral head commonly occurs in the people who are thirty to fifty years old. The most general treatment for early stages of avascular necrosis of the femoral head is core decompression. However, there is no general consensus regarding either the indications for this procedure or the techniques that optimize results. We want to develop a biodegradable and angiogenic bone cement for treatment of avascular necrosis of the hip. Core decompression is followed by injection of bone cement within operation. Bone cement will provide mechanical strength and angiogenic function to increase nutrition supply for bone tissue regeneration. We anticipate the newly formed bone can replace the degraded bone cement and the defect site is able to recovered. Several advantages of poly(propylene fumarate) (PPF) has been investigated, including：biodegradable material and low crosslinking temperature. Calcium phosphate cement (CPC) is bioresorbable and osteoconductive. We combined these two key materials to offer proper mechanical strength for femoral head of patients. By addition of ginsenoside Rg1 which is extracted from panax ginseng as a angiogenic agent, anticipating that this composite can act as a mechanical support at the bone defect site and stimulate bone regeneration simultaneously. The first part of this study is mainly to discuss the influence of three different ratios of CPC to PPF on biocompatibility, mechanical strength, crosslinking temperature and swelling. Results showed bone cement was more biocompatible with increasing the ratio of CPC to PPF. Increasing the ratio of CPC to PPF also strengthened the mechanical strength, reduce the crosslinking temperature and lower swelling effect. In the second part of this study, we chose the optimal ratio of CPC to PPF and mixed them with three different amounts of Rg1. Then the drug release profile was analyzed and the function of released Rg1 was checked. Data revealed the three different ratios of Rg1 to cement shared almost the same pattern in cumulative Rg1 figure. We chose the proper ratio to make extract liquid. Angiogenic function of released Rg1 to human umbilical vein endothelial cell (HUVEC) was tested by tube formation assay within extract liquid. Result showed the released Rg1 was still able to stimulate angiogenesis signficantly. In summary, this bone cement composite possesses great developing potential to be applied on treating avascular necrosis of the femoral head.