Li Y, Ma T, Yang S T, Kniss D A
Department of Chemical Engineering, The Ohio State University, Columbus 43210, USA.
Biomaterials. 2001 Mar;22(6):609-18. doi: 10.1016/s0142-9612(00)00224-6.
Nonwoven fibrous matrices have been widely used as scaffolds in tissue engineering, and modification of microstructure of these matrices is needed to organize cells in three-dimensional space with spatially balanced proliferation and differentiation required for functional tissue development. The method of thermal compression of nonwoven polyethylene terephthalate (PET) fabrics was developed and key parameters of temperature, pressure, and compression duration were evaluated in this study. The permanent deformation was obtained at elevated temperature under pressure and the viscoelastic compressional behaviors were observed, characterized by a distinct apparent modulus change in glass transition temperature region. A liquid extrusion method was further employed to analyze both pore size and its distribution for matrices with porosity ranging from 84 to 93%. It is also found that a more uniformly distributed pore size was resulted from thermal compression and the isotropic nature of nonwoven fabrics was preserved because of the proportional reduction of the pore by compression. The thermally compressed fabric matrices with two different pore sizes (15 and 20 microm in pore radius) were used to culture human trophoblast ED27 and NIH 3T3 cells. It was found that cells cultured in the different pore-size PET matrices had different cell spatial organization and proliferation rates. The smaller pores in the matrix allowed cells to spread better and proliferate faster, while cells in the larger pores tended to form large aggregates and had lower proliferation rate. The thermal compression technique also can be applied to other synthetic fibrous matrices including biodegradable polymers used in tissue engineering to modify the microstructure according to their viscoelastic properties.
非织造纤维基质已被广泛用作组织工程中的支架，为了在三维空间中组织细胞，使其具有功能组织发育所需的空间平衡增殖和分化，需要对这些基质的微观结构进行改性。本研究开发了非织造聚对苯二甲酸乙二酯（PET）织物的热压缩方法，并评估了温度、压力和压缩持续时间等关键参数。在压力作用下，高温时可获得永久变形，并观察到粘弹性压缩行为，其特征是在玻璃化转变温度区域有明显的表观模量变化。进一步采用液体挤出法分析孔隙率在84%至93%范围内的基质的孔径及其分布。还发现热压缩导致孔径分布更均匀，并且由于压缩使孔隙按比例减小，非织造织物的各向同性得以保留。使用两种不同孔径（孔半径分别为15和20微米）的热压缩织物基质培养人滋养层细胞ED27和NIH 3T3细胞。结果发现，在不同孔径的PET基质中培养的细胞具有不同的细胞空间组织和增殖速率。基质中较小的孔隙使细胞能够更好地铺展并更快地增殖，而较大孔隙中的细胞倾向于形成大的聚集体且增殖速率较低。热压缩技术还可应用于其他合成纤维基质，包括组织工程中使用的可生物降解聚合物，以根据其粘弹性特性改变微观结构。
