具有奈米溝脊地形的明膠薄膜對人類脂肪幹細胞神經分化之影響

Abstract

胚胎幹細胞會受到微環境中化學及物理變化的影響，而這些變化是由細胞外基質(ECM)和細胞間的交互作用所產生。它能促進幹細胞的生存、增生及分化能力。然而，具有特殊表面結構(如溝槽、脊、坑或柱)的生物材料能夠模仿微環境中的溝脊表面，使幹細胞感受到材料的彈性及表面圖案。因此我們在明膠(gelatin)表面設計了不同尺寸的奈米溝脊圖案。溝脊圖案的設計能夠被系統化，也能反映出細胞外基質的纖維結構。最重要的是，我們可以輕易地觀察到細胞與表面結構的關係。 在先前的研究中，聚苯乙烯(PS)廣泛地被運用於表面結構製造。然而，聚苯乙烯並非生物相容，亦不可降解。為了更好的生物相容性，我們選用明膠作為材料，並利用微鑄造法(micro-molding)在材料表面製造出奈米溝脊圖案。此外，明膠能和許多交聯劑進行交聯，產生更高的機械強度及可彎曲性。 眾所皆知幹細胞可作為移植治療中神經元的來源之一，而神經元的生成和細胞的方向性有所關連。為了瞭解溝脊圖案對幹細胞的影響，我們在明膠表面製造了不同尺寸的奈米溝脊。其中溝和脊的比例為1:1，寬深比分別為400/100、400/400、800/100和800/400奈米。接著在表面上培養人類脂肪幹細胞(hASCs)以觀察其變化。

The growth of stem cells is influenced by both chemical and physical features of the microenvironment, which is also known as “stem cell niche”. These features are dominated by the extra cellular matrix (ECM) and cell-cell interaction. The stem cell niche facilitates the survival, self-renewing and differentiation capabilities of stem cells. Biomaterials with specific structures such as grooves, ridges, pits, or pillars can mimic the topographic landscape of the niche. Cells can “sense” the mechanical properties and surface patterns, ranging from micro- to nano-scale, of the substrate; hence, different sizes of nano-grooves on gelatin surface were designed. The design of grooves or ridges can be systematically modified and those structures can reflect the fibrillar organization of ECM. Most important of all, the orientation of cells along these structures could be observed easily. In previous studies, polystyrene (PS) was often used because it is easy to fabricate topographic structures. However, PS is not biocompatible and biodegradable. For better biocompatibility, gelatin was chose as the material and fabricated into an ideal nano-grooves films by micro-molding method. On the other hand, gelatin can be crosslinked by using several crosslinking agents, which leads to a higher mechanical strength and better flexibility of the material. It was known that stem cells can be served as a source of neurons in transplantation therapies. The differentiation of neurons is associated with directionality of stem cell. To investigate the effect of topographic cues on stem cells, groove pattern arrays, which ridge to groove ratio is 1:1, with two sizes of widths and depths in nano-scale (W/D: 400/100, 400/400, 800/100 and 800/400 nm), were constructed onto gelatin surfaces. Human adipose-derived stem cells (hASCs) were seeded onto the patterned gelatin and cell proliferation and differentiation were observed.