Troken A, Marion N, Hollister S, Mao J
College of Dental Medicine, Foundation School of Engineering and Applied Sciences, Department of Biomedical Engineering, Columbia University, New York, New York 10032, USA.
Proc Inst Mech Eng H. 2007 Jul;221(5):429-40. doi: 10.1243/09544119JEIM288.
The ultimate goal in the tissue engineering of the synovial joint is to fabricate biologically derived analogues that can replace severely degenerated or traumatized synovial joint components. A number of challenges must be addressed before reaching this ultimate goal. In this report, the relevance of cell seeding density in the synthesis of chondrogenic and osteogenic matrices from human mesenchymal stem cells is explored. Human mesenchymal stem cells (hMSCs) were differentiated into chondrogenic cells and osteogenic cells ex vivo and encapsulated in poly(ethylene glycol) diacrylate (PEGDA) hydrogel at densities of 5 x 106 cells/ml, 40 x 10(6) cells/ml, and 80 x 10(6) cells/ml, in addition to a cell-free poly(ethylene glycol) (PEG) control group (0 x 10(6) cells/ml). Cell-seeded or cell-free PEG constructs were separately incubated in vitro for 4 weeks or implanted in vivo in the dorsum of immunodeficient rats for 4 weeks. In-vitro data demonstrated that hMSC-derived chondrocytes or hMSC-derived osteoblasts maintained their lineages per Safranin O and von Kossa staining after incubation for 4 weeks. The general pattern of initial cell seeding densities of 5 x 10(6) cells/ml, 40 x 10(6) cells/ml, and 80 x 10(6) cells/ml were preserved following in-vitro cultivation. Similarly, in-vivo data revealed that hMSC-derived chondrocytes and hMSC-derived osteoblasts maintained their respective lineages and the pattern of cell-seeding densities. An attempt was made to fabricate a composite construct with PEGDA hydrogel and polycaprolactone (PCL) with designed internal porosity for an osteochondral graft. Various cell-seeding densities as delineated in this report can be realized in the composite PEG-PCL graft. The findings demonstrate that cell-seeding density is likely a key parameter to consider in tissue-engineering design. The source of cells can either be transplanted cells or internally recruited cells.
滑膜关节组织工程的最终目标是制造出能替代严重退变或创伤性滑膜关节部件的生物衍生类似物。在实现这一最终目标之前，必须应对诸多挑战。在本报告中，探讨了细胞接种密度在人骨髓间充质干细胞合成软骨生成和骨生成基质中的相关性。人骨髓间充质干细胞（hMSCs）在体外分化为软骨生成细胞和成骨细胞，并以5×10⁶个细胞/毫升、40×10⁶个细胞/毫升和80×10⁶个细胞/毫升的密度封装在聚（乙二醇）二丙烯酸酯（PEGDA）水凝胶中，此外还有一个无细胞聚（乙二醇）（PEG）对照组（0×10⁶个细胞/毫升）。接种细胞或无细胞的PEG构建体分别在体外孵育4周，或在免疫缺陷大鼠背部体内植入4周。体外数据表明，hMSC来源的软骨细胞或hMSC来源的成骨细胞在孵育4周后，经番红O和冯·科萨染色仍保持其谱系。5×10⁶个细胞/毫升、40×10⁶个细胞/毫升和80×10⁶个细胞/毫升的初始细胞接种密度的总体模式在体外培养后得以保留。同样，体内数据显示，hMSC来源的软骨细胞和hMSC来源的成骨细胞保持了各自的谱系以及细胞接种密度模式。尝试用PEGDA水凝胶和聚己内酯（PCL）制造一种具有设计内部孔隙率的复合构建体用于骨软骨移植。本报告中描述的各种细胞接种密度可在复合PEG-PCL移植物中实现。研究结果表明，细胞接种密度可能是组织工程设计中需要考虑的关键参数。细胞来源可以是移植细胞或内源性募集细胞。
