組織完整性主要是受到周圍環境因子的調控，而這些因子包括了化學因子和物理因子，如生長因子或組織軟硬度。然而一班的體外培養技術是將細胞培養在塑膠培養皿上，但塑膠培養皿其物理特性與體內組織內有很大的差距。近期的研究發展出了幾種水膠的體外培養系統，如膠原蛋白凝膠，可以模擬出體內組織之軟硬度。之前的研究發現，膠原蛋白凝膠可以促進三維組織般的多細胞結構，說明膠原蛋白凝膠較一般體外培養系統更接近於體內的環境。
子宮肌瘤是一種良性腫瘤。過去的研究發現，子宮肌瘤細胞在體外長期培養下會形成球狀的聚集，此類聚集被認為是子宮肌瘤細胞的一個特性。對於細胞聚集的現象，在以往的研究均著重在化學因子或遺傳因子的影響。然而細胞外基質軟硬度對於子宮肌瘤細胞聚集的調控則並不清楚。因此，我們想探討細胞外基質軟硬度在子宮肌瘤細胞形成聚集的過程中所扮演的角色。首先我們研究子宮肌瘤細胞培養於膠原蛋白凝膠培養系統是否較易形成聚集。結果顯示，在膠原蛋白凝膠上相較於培養皿的細胞聚集面積較大且密度較高，並且細胞聚集的速度較快。為了進一步探討細胞基質軟硬度對於子宮肌瘤細胞聚集的影響，我們使用不同來源的膠原蛋白凝膠。結果顯示在較軟的膠原蛋白凝膠上，會加速子宮肌瘤細胞的聚集。我們發現子宮肌瘤細胞會使得膠原蛋白凝膠收縮，由此推測細胞收縮力可能參與在細胞聚集的現象當中。而在給予Rho-kinase抑制劑後，膠原蛋白凝膠上之細胞聚集也受到抑制。以上結果顯示了細胞外基質的軟硬度和細胞的收縮力調控子宮肌瘤細胞的聚集。

The maintenance of tissue integrity is mainly controlled by the environmental cues, such as chemical signals and physical inputs, i.e., tissue stiffness. However, by using in vitro culture technique, cells are always cultured on plastic dish which may not be relevent to the in vivo physical property of tissue. Recent studies have developed several hydrogel systems, such as collagen gel to mimic physiological stiffness of tissue. It has been shown that collagen gel induces three-dimensional tissue-like multicellular structures which are more relevent to in vivo system.
Uterine leiomyoma is a benign tumor grown in myometrium. Smooth muscle cells that derived from leiomyomal form ball-like aggregates whereas normal myometrial cell does not, suggesting that the formation of aggregation is one the major characteristics of leiomyomal cell in vitro. While much effort has been focused on the soluble/genetic factors in the formation of ball-like aggregrates, little is known on ECM stiffness in the regulation of the ball-like aggregrates in leiomyomal cells. Thus, my project is to investigate the role of ECM stiffness in the regulation of ball-like aggregrates in leiomymal cells. First I investigated whether collagen gel culture system induces aggregations of leiomyomal cell. The results showed that leiomyomal cell formed more aggregates when cells were grown on collagen gel but not collagen-coated dish. To further investigate the degree of collagen rigidity affected formation of aggregates, I performed different collagen gels from different origins. The results showed that leiomyomal cell developed cell aggregates on softer collagen gel earlier than stiff one. Leiomyomal cell contracted and resulted in shrinkage of collagen gel, suggesting the involvement of cell contractility in leiomyomal cell aggregation on collagen gel. Pharmacologic inhibition of myosin-II related contractility inhibited the leiomyomal cell aggregation on collagen gel. These results suggest that physical property of substratum and cell contractility regulated formation of leiomyomal cell aggregation.

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