A team of researchers fromCarnegie Mellon Universityhave developed a new method of 3D bioprinting that enables the production of realistic fully-sized human heart models.
The scientists’ Freeform Reversible Embedding of Suspended Hydrogels (FRESH) technique, involves extruding the eco-friendly alginate polymer into a custom-made gelatin container. Leveraging their novel process, the team aims to work with surgeons to create patient-specific clinical models for surgical training and pre-planning applications.
领导该项目的亚当·费恩伯格（Adam Feinberg）教授说：“外科医生可以操纵它，并实际上像真正的组织一样做出反应。”“因此，当他们进入操作站点时，他们在该环境中还具有额外的现实实践。”
“We can now build a model that not only allows for visual planning but allows for physical practice.”
一种“新鲜”的新3D打印方法
An increasing number of surgeons are adopting 3D printing as a means ofdeveloping bespoke models这使他们可以向患者解释心脏程序。使用生物打印来产生这些副本，使它们成为现实，但也打开了将来的组织工程和再生医学应用的可能性。
目前,常见的3 d打印技术,如stereolithography (SLA) and Fused Deposition Modeling (FDM) are being used to reproduce realistic-looking organs. Although such methods have generally yielded positive results, their wider adoption has so far been limited by their cost, and the level of expertise required to manufacture them.
为了克服这些限制，Feinberg教授和他的同事们花了two years researchinghow to print a human heart model in full-size and came up with a FRESH new approach. The team’s novel technique begins with using data gathered from MRI scans and other scanning processes to design an accurate 3D model.
The resulting designs are then printed using a needle measuring 250 microns in diameter, which extrudes alginate into a custom-made container that’s large enough to fit a fully-sized replica. The team’s new method was ultimately found to yield more durable models than before, potentially allowing them to be used more effectively as a surgical training tool.
3D printing the fully-sized surgical models
During the 3D printing process, the scientists adopted alginate as the main material for their models because it closely resembles the texture and mechanical properties of organic cardiac tissue. What’s more, softer materials such as TPUs and silicone show deformations under the force of gravity, making the slightly more rigid alginate a better-suited alternative.
After fabricating a series of prototypes, the researchers post-processed them for 12 hours within a gelatin container, before placing them into an incubator overnight to remove their gelatin supports. Once the additive cardiac models were ready, Feinberg and his team proceeded to test them by seeing how far the polymer could be stretched while being stitched.
结果表明，藻酸盐具有足够的拉伸强度，可以在心脏模型中进行外科医生进行练习。然后，研究人员开始使用新的方法来制造较小的模型，这些模型由冠状动脉组成，这些冠状动脉充满了假血，这对训练外科医生也可能有用。
有趣的是，该团队透露，挤出机的针尖是有问题的，因为它需要足够长的时间才能到达浴室的底部，并支持印刷材料。为了解决此问题，创建了一个3D打印的针支撑项圈，可以随意更换并附着在打印机的挤出机头上。
研究人员得出的结论是，他们的3D模型适合作为练习缝合的手术训练工具，以及可以在真实人心脏上进行的其他操作。总体而言，该项目可以开放其他研究途径，将来，该团队希望他们的新方法能够开发生物医学测试工具。
3D printing and previous matters of the heart
近年来，各种科学家采用3D印刷作为生产逼真的器官模型的一种手段，从而扩大了我们对人体的理解。
In July 2020, theUniversity of Minnesota开发了一种新的生物墨水，帮助他们创建了一个functional 3D printed beating heart由富含细胞的生物材料制成。该团队的新颖材料使他们能够打印出带有更多腔室，心室和高细胞壁厚的主动脉副本。
Earlier this year,The University of Texas at El Paso(UTEP) and biomedical researchers fromTexas Tech University Health Sciences Center El Paso（ttuhsc el paso）一起工作3D print mini-hearts. The cell-laden structures were sent tothe International Space Station（ISS）研究微重力如何影响人心的功能。
Similarly in 2018, a group of doctors from theZhengzhou University进行了研究一组25例highlight how3D printed anatomical modelscould be used in heart operations. The team eventually used CT scans to develop a patient-specific model that could be 3D printed at a 1:1 scale.
The research paper that includes the world’s first full-size 3D printed heart is titled新鲜的3D生物打印人类心脏的全尺寸模型。It is co-authored by Eman Mirdamadi, Joshua W. Tashman, Daniel J. Shiwarski, Rachelle N. Palchesko,和亚当·W·费恩伯格（Adam W. Feinberg）*
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特征图显示了全尺寸的3D印刷成人心脏模型Feinberg及其团队制造的。通过卡内基·梅隆大学的照片。
