血小板經血管受傷快速活化，其內的α顆粒釋放內容物包括生長因子及thrombospondin(TSP)等；生長因子如PDGF、TGF-β可以增加傷口癒合。富含血小板血漿(Platelet-rich plasma, PRP)由自體採血，經過二次離心濃縮為含有大量血小板的血漿；文獻上PRP對於臨床上應用在局部或區域性骨缺損，其加成的效果一直存有爭議。此外，血小板亦富含thrombospondin醣蛋白，其中TSP-1主要已知的功能是抑制血管新生(angiogenesis inhibitor)。也就是說，血小板同時富含正面的生長因子及負面的調控因子，所以兩方面的加減效果對於口腔的傷口癒合，有待實驗加以釐清。本研究目的為評估在活體外PRP及調控因子對口腔相關再生細胞生物功能的影響。
20位志願者參與本實驗抽取靜脈血加以分離出缺乏血小板血漿(PPP)及100-120×10⁴/μl血小板之PRP。以0%、2%、5%、15%、30%新鮮PRP及2%、5%新鮮PPP加入不含血清而含有纖維素原(fibrinogen)及凝血酶(thrombin)之培養液形成膠體後，然後分別置入牙周靭帶纖維母細胞、成骨細胞、內皮細胞於膠體上培養6天，以Alamar blue assay進行細胞增生的檢測、比較不同濃度對這些細胞的增生是否會有影響。以西方墨點法(Western blot)檢測PRP中TSP-1的表現；以酵素連結免疫吸附分析(ELISA)來推估PRP及30%PRP gel上懸浮培養液中TSP-1的量。最後上述細胞培養在相當於PRP膠體懸浮培養液中TSP-1的連續性濃度2天。
結果顯示，三種口腔再生相關的細胞在低濃度PRP膠體上(小於5%) 6天的培養有增加的現象，在高濃度PRP膠體上(15-30%)的培養則呈現減少的趨勢。西方墨點法證明PRP含有高量TSP-1；酵素連結免疫吸附分
析中TSP-1量在PRP溶解液為183.3 ± 21.6 μg/ml以及30% PRP膠體懸
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浮液為9.7 ± 1.6 μg/ml。細胞培養在TSP-1連續性濃度下，2天後呈現隨TSP-1濃度劑量增高而細胞減少的形式。
在本實驗有限的資料中，三種口腔再生相關的細胞在高濃度PRP膠體上的培養呈現統計上減少的趨勢；此外，PRP中含有大量的TSP-1，而TSP-1可能在細胞凋亡扮演重要的角色。

Platelets are rapidly activated by blood vessel injury and release products from the alpha granules containing growth factors, thrombospondin, fibrinogen, etc. The growth factors include platelet-derived growth factor (PDGF) and transforming growth factor-β (TGF-β), which can enhance wound healing. Platelet-rich plasma (PRP) is derived from autologous blood by sequestering and concentrating the platelets via centrifugation. PRP gel is an autologous modification of fibrin glue that has been described and used in various applications, but its clinical results remained controversial. We wanted to know whether a negative regulator exists in PRP, because the major function of thrombospondin-1 (TSP-1) is inhibiting angiogenesis. The aim of this study was to evaluate the regulators on PRP effects and its biological function in vitro.
Twenty volunteers participated in this study and donated their venous blood. Using centrifugation, platelet-poor plasma (PPP) and PRP containing 100-120 × 104/μl platelets were obtained. We added different concentrations of fresh PRP and PPP to cell cultures related to regeneration: periodontal ligament (PDL) fibroblast, osteoblast, and endothelial cell cultures. We measured the rate of cell proliferation using an alamar blue assay for 6 days. Subsequently, after protein concentrations had been determined, the band density of TSP-1 was examined using Western blotting. The quantitation of TSP-1 was estimated using an ELISA assay. Finally, we incubated the cell cultures for 2 days in serial concentrations of TSP-1 that corresponded to 30% PRP gel.
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We found that, after 6 days of incubation, the cells increased in a low concentration of PRP (< 5%) and decreased in a high concentration (15-30%). Western blotting showed that TSP-1 expression was higher in PRP than in PPP. An ELISA assay showed that the quantities of TSP-1 expressed were 183.3 ± 21.6 μg/ml in PRP and 9.7 ± 1.6 μg/ml in the supernatant of 30% PRP gel. The cell culture in serial concentrations of TSP-1 dose-dependently decreased.
Within the limits of the present study, it can be concluded that the number of cells significantly decreased when treated with a high concentration of PRP and that PRP is abundant in TSP-1, which may play an important role in apoptosis.

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