I-Corps: Commercialization of injection molded nanostructured biomedical consumables

指导和调节干细胞的命运是生物科学界面临的主要挑战。细胞行为的控制传统上是通过化学方法完成的；这些方法本质上是有用的，但是细胞稳定性的问题也出现了。目前，细胞是在组织培养处理过的培养皿（由聚苯乙烯或玻璃制成）上生长的。这些产品虽然便宜且容易获得，但会对贴壁细胞产生不良影响。细胞的过早分化和/或衰老现象等影响可能会限制这些细胞在未来细胞治疗中使用的潜力。这个I-Corps团队开发了用于细胞培养的纳米结构多孔板插入物。这些使用注射成型技术生产的纳米结构基质允许干细胞（包括人间充质细胞和其他亚型）在没有进一步化学处理（如氧等离子体、蛋白质涂层或其他表面修饰）的情况下进行稳健培养；有可能降低实验室细胞培养方案的成本。通过制造，纳米结构表面特征的调节（允许干细胞长期培养或控制细胞分化）。因此，各种各样的细胞-基质相互作用将为干细胞的发育和分化提供一个全新的范例，并使这门科学可能以更快的速度转化为临床应用。生物细胞在水平和垂直方向上都施加机械力。然而，一般来说，垂直力与水平细胞力（牵引力）相比是小的。因此，通过这些主要牵引力影响细胞的关键是控制基底在横向的顺应性（弯曲刚度）。考虑到衬底是刚性的，可以应用胡克弹性变形定律，对于微纳米尺度的圆柱柱，可以得到一个可预测的面内力-位移关系。通过精确确定表面特征尺寸和间距，微/纳米结构表面阵列可以设计出一系列有效的侧表面顺应性。由于特征变形是由施加的力决定的，更细的间距将在每个细胞下定位更多的特征，并减少施加在每个细胞上的生物牵引力。为了制造这些特征，该团队利用注射成型作为一种高容量和可重复的方法来创造有利于激发特定细胞功能的表面积。紫外光刻技术，结合深度反应离子蚀刻，用于在相对较大的硅片表面积上产生微特征。微特征硅片然后用作微注射成型工艺的模具插入物，以创建各种热塑性聚合物的表面。改变模具特征可以控制微观几何形状，从而进一步改变聚合物基材的有效表面刚度和细胞的最终行为，从而带来先进的细胞工程机会。

Directing and modulating the fate of stem cells poses a primary challenge in the bioscience community. Control of cell behavior is traditionally accomplished using chemical methods; and these methods are inherently useful, but difficulties with cell stability do arise. Currently, cells are grown on tissue culture treated Petri dishes (made from polystyrene or glass). These products, while inexpensive and readily available, can produce undesirable effects on adherent cells. Effects such as premature differentiation and/or aging phenomenon in cells may limit the potential of these cells to be used in future cell therapeutics. This I-Corps team has developed nano-structured multi-well plate inserts for cell culture. These nano-structured substrates, produced using injection molding techniques allow for robust culture of stem cells (both human mesenchymal and other subtypes) in the absence of further chemical treatments, such as oxygen plasma, protein coatings, or other surface modifications; potentially reducing the cost of laboratory cell culture protocols. Through manufacturing, modulation of the nano-structured surface features (llows for either long-term culture of stem cells or controlled differentiation of the cells. The wide variety of cell-substrata interactions made possible as a result would enable a whole new paradigm for stem cell development and differentiation, and allow this science to possibly translate at a faster rate to clinical applications.Biological cells exert mechanical forces in both the horizontal and vertical directions. In general, however, the vertical forces are small compared to horizontal cellular forces (traction forces). Thus, the key to affecting cells via these dominant traction forces is to control substrate compliance in the lateral direction (flexural stiffness). Considering the substrate to be rigid, Hooke's law of elastic deformation can be applied, which for cylindrical columns at the micro- or nano-scale yields a predictable in-plane force-displacement relationship. With precise determination of surface feature dimensions and spacing, micro/nanostructured surface arrays can be designed to yield a range of effective lateral surface compliances. As feature deformation is dictated by the applied force, a finer pitch will position more features under each cell and produce a reduction of the biological traction forces applied to each one. To manufacture these features, the team has taken advantage of injection molding as a high volume and repeatable method to create surface areas conducive to eliciting specific cellular functions. Ultraviolet lithography, combined with deep reactive ion etching, is used to generate micro-features over a relatively large surface area of a silicon wafer. The micro-featured silicon wafer is then used as a mold insert for the micro-injection molding process to create surfaces from a wide variety of thermoplastic polymers. Altering the mold features controls the micro-geometry, which further alters the effective surface stiffness of the polymer substrate and the resultant behavior of the cells - leading to advanced cellular engineering opportunities.