3D Bioprinted Nipple-Areolar Complex Implants

摘要 美国每年有超过10万名妇女因乳腺癌接受乳房切除术，导致乳房组织损失。乳头乳晕复合体（NAC）是患者乳房组织的关键特征之一，在重建中经常被忽视。对于NAC重建或再生，没有临床上可行的解决方案。这项工作的长期目标是开发一种个性化的、生物可吸收的NAC，为患者提供天然乳头突起的形状。为了实现这一目标，我们开发了一种由两种互补聚合物组成的混合生物材料植入系统，（1）定义NAC的结构，（2）促进组织长入NAC。NAC植入物最终将降解，在其位置留下在大小、形状和质地上与原始组织相似的重建NAC。为此，我们提出三个具体目标。具体目标1将生物打印一个可行的和可翻译的NAC。我们将通过Solidworks生成NAC植入物设计组合，从而快速开发个性化植入物。CAD设计将探索乳头突出高度、乳头直径、乳晕直径和NAC填充图案对植入物性质的影响，特别是对随着时间的推移保持形状的影响。NAC植入物将由可快速平移的生物材料制成。将评估物理和生物学特性（形状、力学、细胞接种效率、细胞活力/增殖、基质生成），并评价单个植入物组件特性和降解。具体目标2将建立一个生物打印NAC的体外培养系统。我们开发了一种专门用于培养生物打印NAC的3D打印生物反应器，因为该结构由于其组织生物学（空气-水界面）和组织结构（非平面投影形状）而呈现出独特的培养挑战。NAC生物反应器将被制造并用于培养生物打印的构建体。将优化培养条件，包括培养基流速，以支持细胞增殖和功能（ECM产生），同时保持NAC系统的形状。最后，Aim 3将使生物打印的NAC血管化。我们认为，临床上可转移的生物打印植入物的成功策略将利用周围宿主组织的血管向内生长并进入NAC。为此，我们将设计和制造一个分层的NAC血管网络，包括打印的微血管和自组装的微血管由宿主组织指导。在我们建立的动物模型的基础上，我们将优化NAC的血管特征（结构，细胞结构），以提供快速建立，充足的营养输送和血管功能的关键结果-同时保持NAC的结构和功能。拟议的工作的结果将是能够产生一个个性化的乳头乳晕复合体，可以植入在土堆重建或在以后的日期。

ABSTRACT Over 100,000 women in the United States undergo mastectomy procedures each year due to breast cancer, resulting in loss of breast tissue. One of the key traits of a patient's breast tissue that is often neglected in reconstruction is the nipple areolar complex (NAC). There is no clinically viable solution for NAC reconstruction or regeneration. The long-term goal of this work is to develop a personalized, bioresorbable NAC that will provide patients with the shape of a native nipple projection. To pursue this goal, we have developed a hybrid biomaterial implant system consisting of two complementary polymers that (1) define the architecture of the NAC and (2) encourages tissue ingrowth into the NAC. The NAC implant will eventually degrade, leaving in its place a reconstructed NAC that is similar to the original tissue in size, shape, and texture. To this end, we suggest three specific aims. Specific Aim 1 will bioprint a viable and translatable NAC. We will generate a portfolio of NAC implant designs via Solidworks, allowing for rapid development of personalized implants. CAD designs will explore the impact of nipple projection height, nipple diameter, areola diameter, and NAC infill patterning upon the implant's properties, and particularly on the retention of shape over time. NAC implants will be fabricated from rapidly translatable biomaterials. Physical and biological properties {shape, mechanics, cell seeding efficiency, cell viability/ proliferation, matrix production) will be assessed, and individual implant component properties and degradation will be evaluated. Specific Aim 2 will establish an in vitro culture system for a bioprinted NAC. We have developed a 3D printed bioreactor specifically for the culture of a bioprinted NAC, as the construct presents unique culture challenges due to its tissue biology (air-water interface) and tissue architecture (non-planar projection shape). NAC bioreactors will be fabricated and employed to culture the bioprinted constructs. Culture conditions, including media flow rate, will be optimized to support cell proliferation and function (ECM production), while maintaining shape of the NAC system. Finally, Aim 3 will vascularize a bioprinted NAC. We suggest that the successful strategy for a clinically translatable bioprinted implant will utilize vascular ingrowth from the surrounding host tissue and into the NAC. To this end, we will design and fabricate a hierarchical NAC vasculature network consisting of a printed microvasculature and a self-assembled microvasculature directed by host tissue. Furthering our established animal model, we will optimize the NAC's vasculature features (architecture, cellularity) to deliver the critical outcomes of rapid establishment, sufficient nutrient delivery, and vascular functionality- while maintaining the NAC's structure and function. The result of the proposed work will be the ability to produce a personalized nipple areolar complex that can be implanted during mound reconstruction or at a later date.