生物體外微血管叢的培養研究在組織工程與再生醫學領域中至關重要。血管內皮生長因子(VEGF)是誘導微血管生成的主要訊號蛋白之一，其可溶解於細胞培養液中，亦可與生物凝膠中的特定蛋白質成分形成鍵結。然而目前促成微血管發育的完整驅動機制仍不清楚，學者們之主流共識為鍵結型血管內皮生長因子主導細胞遷徙，相反地溶解型血管內皮生長因子的作用則在多數研究中被忽略不計。另一方面，依據生長因子誘發細胞運動建立的化學機轉理論模型，與考量細胞貼附於生物凝膠材料的傳統力學平衡模型之間，目前亦缺乏有系統的聯繫。本論文首先設計了一系列實驗，以探討兩種型式血管內皮生長因子在微血管生成過程所扮演的角色，利用包含膠原蛋白與纖維網蛋白之自製簡易生物凝膠，於生物體外培養人類臍靜脈內皮細胞，最終形成完整的類微血管細胞網路。實驗結果表明溶解型生長因子可誘導內皮細胞發生形態轉變，骨架拉伸後之細長形細胞將有助於微血管形成；同時鍵結型生長因子提供具有方向性之細胞趨觸性訊號，促使內皮細胞遷徙聚集，以維持整體細胞網路之穩定。其後依據實驗發現，本論文建構了一套混合數學模型以模擬微血管的生長過程。其中採用離散之細胞帕茲模型預測每一隻內皮細胞的運動方式，並使用偏微分方程式計算生物凝膠的變形程度以及生長因子的分布動態。計算結果顯示了預測之細胞網路拓撲與實驗影像具有良好的一致性，並表明只有當力學與化學機轉充分發揮作用時，方能得到高度發育之微血管網路結構。;Capillary plexus cultivation is crucial in tissue engineering and regenerative medicine. Vascular endothelial growth factor (VEGF) is one of the primary signal proteins stimulating blood vessel formation, which can be soluble in the medium or protein-bound to the substrate. However, less attention has been paid to distinguishing the specific stimulations by soluble and bound form. On the other hand, theoretical simulations have also been conducted to supplement the expensive experimental works, whereas the mechanisms connecting mechanical and chemical stimuli remained undefined. In this paper, a series of experiments were conducted to explore the respective effects of the two VEGF forms. An in-house synthesized biogel comprising a definite concentration of collagen and fibronectin was designed to cultivate human umbilical vein endothelial cells to form capillary-like networks. The results indicated that the soluble VEGF promptly induced the cells to morphologize from round to elongated shape, which contributed to forming network cords. Simultaneously, the bound VEGF provided long-term stimulation, causing the cells to migrate and differentiate into the final capillary-like network. Furthermore, a hybrid model was developed for simulating short-term in vitro capillary incubation, where the cellular Potts model was used to predict individual cell migration, and continuum mechanics to quantify biogel deformation and VEGF transport dynamics. By bridging the mechanical regulation and chemical stimulation in the model, the results showed good agreement between the predicted network topology and experiments. These results revealed that the capillary-like networks could develop in high integrity only when the mechanical and chemical couplings worked adequately, with the cell morphology and haptotaxis driven by the two forms of VEGF functioning simultaneously.
