科学家在实验室使用人的成体干细胞培育出部分颚骨。他们指出，这是第一次通过这种方法制成复杂的大小适合于解剖的骨骼，他们希望这种技术不仅能治疗这种特殊关节的疾病，还能矫正其他骨骼的问题。
哥伦比亚大学的这个研究结果公布在《美国科学院院刊》上。实验室合成的骨骼是颞下颌关节。这一关节的问题可能由出生缺陷、关节炎或者损伤造成。虽然该关节的问题很常见，但它很难治疗。该关节有着复杂的结构，这使得它很难通过移植身体其他部位的骨骼进行修复。
在这项新研究中，科学家用到了人骨髓中的干细胞。他们把这些干细胞植入一个组织架中，借助患者的数码成像形成精确的人下巴骨形状。然后他们使用特殊设计的生物反应器培育细胞，这种反应器能让成长的组织浸泡在自然骨骼生长所需要的含量精确的营养成分中。
该研究第一研究人员戈达纳·伍加克·诺瓦科维克说：“使用患者自身干细胞的骨骼移植的可行性将会革新我们目前治疗这种缺陷的方法。”伍加克·诺瓦科维克称，这种新技术还可能用于头部和颈部的其他骨骼，包括很难移植的头骨和颧骨。
用这种方法制造大小适合于解剖的人骨可能会潜在地改变医生执行整形手术的能力，如严重受损后或癌症治疗。她说：“我们认为下颚骨是对我们技术的最严峻的考验，只要这一问题得到解决，你就可以制作任何形状。”她强调在实验室里合成的关节只是骨骼，不包括其他组织，如软骨。但是，哥伦比亚研究组正在研究一种包括骨骼和软骨的混杂移植的新方法。
科学家面临的一大挑战是找到有血液供应的骨骼的合成方法，这样就容易与宿主的血液供应连接。去年帮助合成人工气管的布里斯托尔大学的组织工程专家安东尼·霍伦德教授称，在新骨骼用于患者前还需要做大量工作。但是，他说：“科学家在该领域面对的重要问题之一是如何合成有着合适维度的一块骨骼，对一些骨骼缺陷来说这很重要。现在，科学家已经合成形状高度精确的骨骼，这是组织工程学中令人欣慰的一面。”（生物谷Bioon.com）
生物谷推荐原始出处：
PNAS October 9, 2009, doi: 10.1073/pnas.0905439106
Engineering anatomically shaped human bone grafts
Warren L. Graysona, Mirjam Fr?hlicha,b, Keith Yeagera, Sarindr Bhumiratanaa, M. Ete Chanc, Christopher Cannizzarod, Leo Q. Wana, X. Sherry Liuc, X. Edward Guoc and Gordana Vunjak-Novakovica,1
aLaboratory for Stem Cells and Tissue Engineering, Department of Biomedical Engineering, Columbia University, 622 West 168th Street, VC 12-234, New York, NY 10032;
bEducell Ltd., Letaliska 33, 1000 Ljubljana, Slovenia;
cBone Bioengineering Laboratory, Department of Biomedical Engineering, Columbia University, 351 Engineering Terrace, 1210 Amsterdam Avenue, MC 8904, New York, NY 10027; and
dDepartment of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155
The ability to engineer anatomically correct pieces of viable and functional human bone would have tremendous potential for bone reconstructions after congenital defects, cancer resections, and trauma. We report that clinically sized, anatomically shaped, viable human bone grafts can be engineered by using human mesenchymal stem cells (hMSCs) and a “biomimetic” scaffold-bioreactor system. We selected the temporomandibular joint (TMJ) condylar bone as our tissue model, because of its clinical importance and the challenges associated with its complex shape. Anatomically shaped scaffolds were generated from fully decellularized trabecular bone by using digitized clinical images, seeded with hMSCs, and cultured with interstitial flow of culture medium. A bioreactor with a chamber in the exact shape of a human TMJ was designed for controllable perfusion throughout the engineered construct. By 5 weeks of cultivation, tissue growth was evidenced by the formation of confluent layers of lamellar bone (by scanning electron microscopy), markedly increased volume of mineralized matrix (by quantitative microcomputer tomography), and the formation of osteoids (histologically). Within bone grafts of this size and complexity cells were fully viable at a physiologic density, likely an important factor of graft function. Moreover, the density and architecture of bone matrix correlated with the intensity and pattern of the interstitial flow, as determined in experimental and modeling studies. This approach has potential to overcome a critical hurdle—in vitro cultivation of viable bone grafts of complex geometries—to provide patient-specific bone grafts for craniofacial and orthopedic reconstructions.
