Engineering of Vascularized Bone

项目概要 在手术重建因以下原因引起的骨骼缺损时迫切需要骨移植 创伤、慢性疾病、肿瘤切除和先天性异常。骨组织工程提供 改变骨骼重建临床实践的巨大潜力。然而，几个 关键障碍限制了骨组织工程转化为临床实践。 重要的是，骨组织工程的关键障碍之一不是骨本身；而是骨。相反，它是 血管化不理想。我们和其他人的新兴工作已经开始探索令人兴奋的 两个独特的干细胞/祖细胞群之间的串扰，这些干细胞/祖细胞产生骨和 血管生成，即间充质干细胞（MSC）和造血干细胞（HSC）。 通过 HSC 和 MSC 联合移植进行生物工程血管生成与目前的技术不同 血管生成方法包括生长因子输送或制造血管类似物。在 在发育过程中，HSC 和 MSC 协同作用，诱导（血管化）成骨。在 成人中，间充质干细胞与造血干细胞共存于骨髓微环境中，其他基质细胞也是焦点 关于加强研究。 MSC 传统上被分离为贴壁细胞（组织培养 聚苯乙烯）由骨组织工程界，而非粘附的HSC通常是 被丢弃。正如 PloS One 最近的一份报告所记录的，我们的初步数据表明，共同 MSC 和 HSC 谱系移植产生血管化异位骨，比 单独移植MSC或HSC。这些发现以及 MSC-HSC 的最新发现 其他人的相互交谈，激发了我们共同移植 MSC 和 HSC 的中心假设 在原位模型中再生血管化骨。颅骨缺损代表了广泛的 利用模型进行骨愈合和重大临床挑战。目前的骨替代品如 羟基磷灰石和移植物低于外科医生的预期。据此，本次活动的总体目标 提议是通过 HSC 和 HSC 的协同作用在体内原位设计血管化骨 间充质干细胞。尽管 HSC 和 MSC 的联合移植代表了骨组织中的一个新概念 工程方面，我们认为需要了解大量的基础生物学知识，其中一些 在将该方法转化为临床环境之前，本提案中计划了这些内容。安 我们将探索令人兴奋的潜力，因为我们的长期目标是可以分离 MSC 和 HSC 在一次门诊骨髓抽吸手术中，并进行最小程度的操作以再生 血管依赖性组织，如骨、脂肪、神经和真皮移植物。

Project Summary Bone grafts are critically needed in the surgical reconstruction of skeletal defects resulting from trauma, chronic diseases, tumor removal and congenital anomalies. Bone tissue engineering offers tremendous potential in transforming the clinical practice of skeletal reconstruction. However, several critical barriers have restricted the translation of bone tissue engineering into clinical practice. Importantly, one of the key barriers in bone tissue engineering is not bone per se; instead, it is suboptimal vascularization. Emerging work from us and others has begun to explore an exciting cross-talk between two distinctive populations of stem/progenitor cells that generate bone and angiogenesis, namely mesenchymal stem cells (MSCs) and hematopoietic stem cells (HSCs). Bioengineered angiogenesis by co-transplantation of HSCs and MSCs is a departure from current angiogenesis approaches including growth factor delivery or fabricating blood vessel analogs. In development, HSCs and MSCs function synergistically to induce (vascularized) osteogenesis. In the adult, MSCs co-reside with HSCs in bone marrow niches among other stromal cells that are the focus on intensifying studies. MSCs are conventionally isolated as adherent cells (to tissue culture polystyrene) by bone tissue engineering community, whereas non-adherent HSCs are conventionally discarded. Our preliminary data, as documented in a recent report in PloS One, demonstrate that co- transplantation of MSC and HSC lineages yielded vascularized ectopic bone, more significantly than the transplantation of MSC or HSC alone. These findings, and also recent discoveries of MSC-HSC cross-talk by others, have motivated our central hypothesis that co-transplanted MSCs and HSCs regenerate vascularized bone in an orthotopic model. The calvarial defect represents a widely utilized model for bone healing and substantial clinical challenges. Current bone substitutes such as hydroxyapatite and grafts are below the surgeon's expectations. Accordingly, the overall goal of this proposal is to engineer vascularized bone in vivo orthotopically from synergistic actions of HSCs and MSCs. Although co-transplantation of HSCs and MSCs represents a novel concept in bone tissue engineering, we believe that a great deal of fundamental biology needs to be understood, some of which are planned in this proposal, prior to the translation of this approach to clinical setting. An exciting potential that will be explored as our long-term goal is that MSCs and HSCs can be isolated in a single outpatient bone marrow aspiration procedure, and minimally manipulated to regenerate vasculature-dependent tissues such as bone, adipose, nerve and dermal grafts.