軟骨組織工程是一種適合應用於受損軟骨組織之組織修復及再生的新技術。而在組織工程中，最重要的三大要素包含有細胞的使用，支架以及力學上的刺激。支架的表面化學性質與物理特性對於細胞支架來說是一個足以刺激並影響細胞行為的重要因素。而在力學刺激的應用上來說，動態靜水壓刺激是影響天然軟骨的一個最重要的力學刺激來源。到目前為止，已經有許多研究探討利用動態靜水壓刺激去影響細胞的行為；然而，細胞的行為會因為壓力施加的不同大小、頻率以及壓力持續施加的時間而有不同的影響。因此，這些刺激因素是依據支架和細胞的種類而有所差異。因此，本篇研究的目的主要是利用幾丁聚醣和透明質酸兩類天然性材料以表面修飾的方法製備出三維親水性聚乳酸聚甘醇酸共聚物，並且探討其親水性支架的物理特性及生物相容性比較。之後將豬的軟骨細胞分別植入支架中並以動態靜水壓生物反應器對軟骨細胞作動態靜水壓刺激。本篇研究使用的動態靜水壓刺激參數為壓力大小為2.24 MPa，使用頻率為0.1 Hz，對細胞進行每次刺激30分鐘，每個禮拜刺激兩次連續刺激28天。其細胞支架會在培養過程中的特定時間點－分別是第3天、第7天、第14天、第21天和第28天將細胞支架取出分別進行生物化學及生物力學測試。
結果中指出利用鹽析法以及之後的表面修飾可完整的製備出聚乳酸聚甘醇酸-透明質酸支架、聚乳酸聚甘醇酸-幾丁聚醣支架以及聚乳酸聚甘醇酸-透明質酸-幾丁聚醣支架。而在支架的體外細胞毒性測試中發現聚乳酸聚甘醇酸支架、聚乳酸聚甘醇酸-透明質酸支架、聚乳酸聚甘醇酸-幾丁聚醣支架以及聚乳酸聚甘醇酸-透明質酸-幾丁聚醣支架皆不會在降解的過程中產生過多的酸降解產物而對軟骨細胞造成傷害。在細胞生物相容性和細胞活性比較的結果顯示出每一個三維親水性的支架皆適合做為細胞生長的環境。進一步的在支架力學性質的分析結果中顯示出在4週的培養時間內，聚乳酸聚甘醇酸-透明質酸-幾丁聚醣支架表現出最好且最穩定的楊式係數。此外，在細胞增生的分析上也發現，動態靜水壓組的細胞增生表現量比靜態培養組來得高。而且動態靜水壓組的細胞外基質合成量也比靜態培養組來的多。在一氧化氮的分析中可發現在靜態組以及動態靜水壓培養組中都不會因為產出大量的一氧化氮而誘導細胞退化，甚至是細胞凋亡。整體來說，我們的實驗顯示出聚乳酸聚甘醇酸支架在經過透明質酸與幾丁聚醣的表面修飾後皆能擁有良好的細胞生物相容性，尤其是聚乳酸聚甘醇酸-透明質酸-幾丁聚醣支架組。另一方面也證實了軟骨細胞在經過動態靜水壓培養後的確能增加細胞增生及細胞外基質的合成，並且表現量比靜態培養組來得高。此外，靜態培養組與動態靜水壓組的培養環境皆不會因產生過多的一氧化氮而造成細胞退化。因此，此親親水性三維支架並且結合動態靜水壓生物反應器的力學刺激確實能有效改善軟骨細胞的增生及細胞外基質的合成，可做為適合軟骨修復的新方法。

Tissue engineering of cartilage is emerging as a technique for the regeneration or repair of damaged cartilage tissue. The basic approaches of tissue engineering involve the use of cells, scaffolds and mechanical stimulation. Surface chemistry and mechanical property of scaffold for cells are known as determined factors to stimulate cell behavior. For mechanical stimulation, hydrodynamic pressure is an important mechanical stimulation for native cartilage. At present, many studies used hydrodynamic pressure to stimulate cell culture, however, variety in the magnitude, frequency and duration of hydrodynamic pressure applications gave rise to inconsistence in overall outcome. The optimal hydrodynamic pressure parameters for the magnitudes, frequency and application time are scaffold and cell types dependent. Therefore, the purpose of this study is to modify the 3-D hydrophilic biocompatible PLGA with hydrophilic chitosan, hyaluronan (HA) or chitosan/HA and characterize their physical and biocompatible properties, then seed swine chondrocytes into the scaffolds and stimulate the construct with hydrodynamic pressure bioreactor. We used 2.24 MPa of hydrodynamic pressure at 0.1 Hz for 30 minutes, twice a week for 28 days. Each sample was removed after hydrodynamic pressure at day 3, 7, 14, 21 and 28 for biochemical and biomechanical analysis.
The results showed that the PLGA-HA, PLGA-Chitosan and PLGA-HA-Chitosan scaffolds could be fabricated by salt leaching and further surface modified. The in vitro cytotoxicity test of scaffold for the degradation products of PLGA, PLGA-HA, PLGA-Chitosan and PLGA-HA-Chitosan scaffolds were non-toxic to chondrocytes. The cell biocompatibility and cell viability tests showed these scaffolds were suitable for cell growth. In the mechanical property analysis, the PLGA-HA-Chitosan scaffold had the best and more stable Young’s modulus during 4 weeks of culture. Moreover, the cell proliferation of hydrodynamic pressure group was better than static culture. The glycosaminoglycan content (GAG) production from chondrocytes showed the hydrodynamic pressure group had better performance than static culture group. The nitric oxide content indicated that both static culture group and hydrodynamic pressure group didn’t produce significant amount of nitric oxide to induce cell apoptosis. In conclusion, our study had showed PLGA scaffold after surface modified with hyaluronic acid and chitosan had good cell biocompatibility, especially PLGA-HA-Chitosan group; hydrodynamic pressure bioreactor enhanced more cell proliferation and glycosaminoglycan content than static culture. Both culture conditions did not induce cell degeneration. Therefore, the hydrophilic PLGA scaffolds with hydrodynamic pressure application truly have the potential for cartilage repair.

1. Schulz, R.M. and A. Bader, Cartilage tissue engineering and bioreactor systems for the cultivation and stimulation of chondrocytes. Eur Biophys J, 2007. 36(4-5): p. 539-68.
2. Nesic, D., et al., Cartilage tissue engineering for degenerative joint disease. Adv Drug Deliv Rev, 2006. 58(2): p. 300-22.
3. Cindy Chung, J.A.B., Engineering cartilage tissue. Advanced Drug Delivery Reviews, 2007. 60: p. 243-262.
4. Sandell, L.J. and T. Aigner, Articular cartilage and changes in arthritis. An introduction: cell biology of osteoarthritis. Arthritis Res, 2001. 3(2): p. 107-13.
5. Chung, C. and J.A. Burdick, Engineering cartilage tissue. Advanced Drug Delivery Reviews, 2008. 60(2): p. 243-262.
6. Michael D. Buschmann1, Yehezkiel A. Gluzband1, Alan J. Grodzinsky1,* and Ernst B. Hunziker2, Mechanical compression modulates matrix biosynthesis in chondrocyte/agarose culture. Journal of Cell Science, 1995. 108: p. 1497-1508.
7. Manicourt, D., et al., Application of new techniques to separation of proteoglycan aggregates from normal and destabilized rabbit articular cartilages. Acta Biol Hung, 1984. 35(2-4): p. 137-42.
8. Muller, F.J., et al., Centrifugal and biochemical comparison of proteoglycan aggregates from articular cartilage in experimental joint disuse and joint instability. J Orthop Res, 1994. 12(4): p. 498-508.
9. Lippiello, L., et al., In vitro metabolic response of articular cartilage segments to low levels of hydrostatic pressure. Connect Tissue Res, 1985. 13(2): p. 99-107.
10. Elder, B.D. and K.A. Athanasiou, Effects of Temporal Hydrostatic Pressure on Tissue-Engineered Bovine Articular Cartilage Constructs. Tissue Engineering Part A, 2009. 15(5): p. 1151-1158.
11. Darling, E.M. and K.A. Athanasiou, Articular cartilage Bioreactors and bioprocesses. Tissue Engineering, 2003. 9(1): p. 9-26.
12. Buschmann, M.D., et al., Mechanical Compression Modulates Matrix Biosynthesis in Chondrocyte Agarose Culture. Journal of Cell Science, 1995. 108: p. 1497-1508.
13. Elder, B.D. and K.A. Athanasiou, Hydrostatic Pressure in Articular Cartilage Tissue Engineering: From Chondrocytes to Tissue Regeneration. Tissue Engineering Part B-Reviews, 2009. 15(1): p. 43-53.
14. Parkkinen, J.J., et al., Effects of cyclic hydrostatic pressure on proteoglycan synthesis in cultured chondrocytes and articular cartilage explants. Arch Biochem Biophys, 1993. 300(1): p. 458-65.
15. Buschmann, M.D., et al., Stimulation of aggrecan synthesis in cartilage explants by cyclic loading is localized to regions of high interstitial fluid flow. Arch Biochem Biophys, 1999. 366(1): p. 1-7.
16. Mizuno, S., et al., Hydrostatic fluid pressure enhances matrix synthesis and accumulation by bovine chondrocytes in three-dimensional culture. J Cell Physiol, 2002. 193(3): p. 319-27.
17. Fioravanti, A., et al., Effect of hyaluronic acid (MW 500-730 kDa) on proteoglycan and nitric oxide production in human osteoarthritic chondrocyte cultures exposed to hydrostatic pressure. Osteoarthritis Cartilage, 2005. 13(8): p. 688-96.
18. Nedelec, E., et al., Stimulation of cyclooxygenase-2-activity by nitric oxide-derived species in rat chondrocyte: lack of contribution to loss of cartilage anabolism. Biochem Pharmacol, 2001. 61(8): p. 965-78.
19. Grigolo, B., et al., Down regulation of degenerative cartilage molecules in chondrocytes grown on a hyaluronan-based scaffold. Biomaterials, 2005. 26(28): p. 5668-76.
20. Nicodemus, G.D., I. Villanueva, and S.J. Bryant, Mechanical stimulation of TMJ condylar chondrocytes encapsulated in PEG hydrogels. J Biomed Mater Res A, 2007. 83(2): p. 323-31.
21. Studer, R.K., et al., Nitric oxide inhibition of IGF-1 stimulated proteoglycan synthesis: role of cGMP. J Orthop Res, 2003. 21(5): p. 914-21.
22. Chang, C.H., et al., Tissue engineering-based cartilage repair with allogenous chondrocytes and gelatin-chondroitin-hyaluronan tri-copolymer scaffold: A porcine model assessed at 18, 24, and 36 weeks. Biomaterials, 2006. 27(9): p. 1876-88.
23. Chen, A.C., et al., Chondrocyte transplantation to articular cartilage explants in vitro. J Orthop Res, 1997. 15(6): p. 791-802.
24. Hunziker, E.B., Articular cartilage repair: basic science and clinical progress. A review of the current status and prospects. Osteoarthritis Cartilage, 2002. 10(6): p. 432-63.
25. Marlovits, S., et al., Cartilage repair: Generations of autologous chondrocyte transplantation. European Journal of Radiology, 2006. 57(1): p. 24-31.
26. Vacanti, J.P. and R. Langer, Tissue engineering: the design and fabrication of living replacement devices for surgical reconstruction and transplantation. Lancet, 1999. 354 Suppl 1: p. SI32-4.
27. Brochhausen, C., et al., Cartilage tissue engineering - Innovative scaffold design and new structural characterization methods. Tissue Engineering Part A, 2008. 14(5): p. 709-709.
28. Cheung, H.Y., et al., A critical review on polymer-based bio-engineered materials for scaffold development. Composites Part B-Engineering, 2007. 38(3): p. 291-300.
29. Woodfield, T.B.F., et al., Scaffolds for tissue engineering of cartilage. Critical Reviews in Eukaryotic Gene Expression, 2002. 12(3): p. 209-236.
30. Wang, X., et al., Tissue engineering of biphasic cartilage constructs using various biodegradable scaffolds: an in vitro study. Biomaterials, 2004. 25(17): p. 3681-8.
31. Takezawa, T., A strategy for the development of tissue engineering scaffolds that regulate cell behavior. Biomaterials, 2003. 24(13): p. 2267-2275.
32. Stoop, R., Smart biomaterials for tissue engineering of cartilage. Injury-International Journal of the Care of the Injured, 2008. 39: p. S77-S87.
33. Ouyang, H.W., et al., The efficacy of bone marrow stromal cell-seeded knitted PLGA fiber scaffold for Achilles tendon repair. Ann N Y Acad Sci, 2002. 961: p. 126-9.
34. Qin, L., et al., Enlargement of remaining patella after partial patellectomy in rabbits. Med Sci Sports Exerc, 1999. 31(4): p. 502-6.
35. Baek, C.H. and Y.J. Ko, Characteristics of tissue-engineered cartilage on macroporous biodegradable PLGA scaffold. Laryngoscope, 2006. 116(10): p. 1829-34.
36. Baek, C.H., et al., Tissue-engineered cartilage on biodegradable macroporous scaffolds: cell shape and phenotypic expression. Laryngoscope, 2002. 112(6): p. 1050-5.
37. Hu, X., et al., Preparation and cell affinity of microtubular orientation-structured PLGA(70/30) blood vessel scaffold. Biomaterials, 2008. 29(21): p. 3128-36.
38. Wen, S.J., et al., [Blood vessel tissue engineering: seeding vascular smooth muscle cells and endothelial cells sequentially on biodegradable scaffold in vitro]. Zhonghua Yi Xue Za Zhi, 2005. 85(12): p. 816-8.
39. Zhang, L., et al., A sandwich tubular scaffold derived from chitosan for blood vessel tissue engineering. J Biomed Mater Res A, 2006. 77(2): p. 277-84.
40. Meikle, M.C., et al., Effect of poly DL-lactide--co-glycolide implants and xenogeneic bone matrix-derived growth factors on calvarial bone repair in the rabbit. Biomaterials, 1994. 15(7): p. 513-21.
41. Khan, Y.M., D.S. Katti, and C.T. Laurencin, Novel polymer-synthesized ceramic composite-based system for bone repair: an in vitro evaluation. J Biomed Mater Res A, 2004. 69(4): p. 728-37.
42. Gomes, A.J., et al., Identification of psoralen loaded PLGA microspheres in rat skin by light microscopy. Micron, 2008. 39(1): p. 40-4.
43. Bandi, N., et al., Intratracheal budesonide-poly(lactide-co-glycolide) microparticles reduce oxidative stress, VEGF expression, and vascular leakage in a benzo(a)pyrene-fed mouse model. J Pharm Pharmacol, 2005. 57(7): p. 851-60.
44. VandeVord, P.J., et al., Evaluation of the biocompatibility of a chitosan scaffold in mice. J Biomed Mater Res, 2002. 59(3): p. 585-90.
45. Alves da Silva, M.L., et al., Chitosan/polyester-based scaffolds for cartilage tissue engineering: Assessment of extracellular matrix formation. Acta Biomater, 2009.
46. Subramanian, A. and H.Y. Lin, Crosslinked chitosan: its physical properties and the effects of matrix stiffness on chondrocyte cell morphology and proliferation. J Biomed Mater Res A, 2005. 75(3): p. 742-53.
47. Thein-Han, W.W., Y. Kitiyanant, and R.D.K. Misra, Chitosan as scaffold matrix for tissue engineering. Materials Science and Technology, 2008. 24(9): p. 1062-1075.
48. Price, R.D., M.G. Berry, and H.A. Navsaria, Hyaluronic acid: the scientific and clinical evidence. J Plast Reconstr Aesthet Surg, 2007. 60(10): p. 1110-9.
49. Necas, J., et al., Hyaluronic acid (hyaluronan): a review. Veterinarni Medicina, 2008. 53(8): p. 397-411.
50. Laurent, T., The Biology of Hyaluronan - Introduction. Ciba Foundation Symposia, 1989. 143: p. 1-5.
51. Yoo, H.S., et al., Hyaluronic acid modified biodegradable scaffolds for cartilage tissue engineering. Biomaterials, 2005. 26(14): p. 1925-1933.
52. Lindenhayn, K., et al., Retention of hyaluronic acid in alginate beads: aspects for in vitro cartilage engineering. J Biomed Mater Res, 1999. 44(2): p. 149-55.
53. Larsen, N.E., et al., Effect of hylan on cartilage and chondrocyte cultures. J Orthop Res, 1992. 10(1): p. 23-32.
54. Peyron, J.G. and E.A. Balazs, Preliminary clinical assessment of Na-hyaluronate injection into human arthritic joints. Pathol Biol (Paris), 1974. 22(8): p. 731-6.
55. Namiki, O., H. Toyoshima, and N. Morisaki, Therapeutic effect of intra-articular injection of high molecular weight hyaluronic acid on osteoarthritis of the knee. Int J Clin Pharmacol Ther Toxicol, 1982. 20(11): p. 501-7.
56. Shichikawa, K., A. Maeda, and N. Ogawa, [Clinical evaluation of sodium hyaluronate in the treatment of osteoarthritis of the knee]. Ryumachi, 1983. 23(4): p. 280-90.
57. Dixon, A.S., et al., Clinical trial of intra-articular injection of sodium hyaluronate in patients with osteoarthritis of the knee. Curr Med Res Opin, 1988. 11(4): p. 205-13.
58. Gemmiti, C.V. and R.E. Guldberg, Fluid flow increases type II collagen deposition and tensile mechanical properties in bioreactor-grown tissue-engineered cartilage. Tissue Eng, 2006. 12(3): p. 469-79.
59. Freed, L.E., et al., Chondrogenesis in a cell-polymer-bioreactor system. Exp Cell Res, 1998. 240(1): p. 58-65.
60. Bueno, E.M., B. Bilgen, and G.A. Barabino, Wavy-walled bioreactor supports increased cell proliferation and matrix deposition in engineered cartilage constructs. Tissue Eng, 2005. 11(11-12): p. 1699-709.
61. Freyria, A.M., et al., Optimization of dynamic culture conditions: effects on biosynthetic activities of chondrocytes grown in collagen sponges. Tissue Eng, 2005. 11(5-6): p. 674-84.
62. Bancroft, G.N., et al., Fluid flow increases mineralized matrix deposition in 3D perfusion culture of marrow stromal osteoblasts in a dose-dependent manner. Proc Natl Acad Sci U S A, 2002. 99(20): p. 12600-5.
63. Benjamin D. Elder, P.D., and Kyriacos A. Athanasiou, Effects of Temporal Hydrostatic Pressure
on Tissue-Engineered Bovine Articular Cartilage Constructs. 2009. TISSUE ENGINEERING: Part A: p. 1151-1158.
64. Toyoda, T., et al., Hydrostatic pressure modulates proteoglycan metabolism in chondrocytes seeded in agarose. Arthritis and Rheumatism, 2003. 48(10): p. 2865-2872.
65. Takahashi, K., et al., Hydrostatic pressure influences mRNA expression of transforming growth factor-beta 1 and heat shock protein 70 in chondrocyte-like cell line. Journal of Orthopaedic Research, 1997. 15(1): p. 150-158.
66. Scherer, K., et al., The influence of oxygen and hydrostatic pressure on articular chondrocytes and adherent bone marrow cells in vitro. Biorheology, 2004. 41(3-4): p. 323-333.
67. Hall, A.C., J.P.G. Urban, and K.A. Gehl, The Effects of Hydrostatic-Pressure on Matrix Synthesis in Articular-Cartilage. Journal of Orthopaedic Research, 1991. 9(1): p. 1-10.
68. Lee, D.A. and D.L. Bader, Compressive strains at physiological frequencies influence the metabolism of chondrocytes seeded in agarose. J Orthop Res, 1997. 15(2): p. 181-8.
69. Shogo M., K.S.F., Furukawa., Takashi U., Yasuo N., Tetsuya T, Static and dynamic mechanical properties of extracellular matrix synthesized by cultured chondrocytes. Mater Sci Eng, 2004. 24: p. 425-429.
70. Steinmeyer, J., B. Ackermann, and R.X. Raiss, Intermittent cyclic loading of cartilage explants modulates fibronectin metabolism. Osteoarthritis and Cartilage, 1997. 5(5): p. 331-341.
71. Luo, Z.J. and B.B. Seedhom, Light and low-frequency pulsatile hydrostatic pressure enhances extracellular matrix formation by bone marrow mesenchymal cells: an in-vitro study with special reference to cartilage repair. Proceedings of the Institution of Mechanical Engineers Part H-Journal of Engineering in Medicine, 2007. 221(H5): p. 499-507.
72. MAKOTO KAWANISHI et al., Redifferentiation of Dedifferentiated Bovine Articular Chondrocytes Enhanced by Cyclic Hydrostatic Pressure Under a Gas-Controlled System. TISSUE ENGINEERING, 2007. 13: p. 957-965.
73. Smith, R.L., et al., In vitro stimulation of articular chondrocyte mRNA and extracellular matrix synthesis by hydrostatic pressure. J Orthop Res, 1996. 14(1): p. 53-60.
74. Ikenoue, T., et al., Mechanoregulation of human articular chondrocyte aggrecan and type II collagen expression by intermittent hydrostatic pressure in vitro. J Orthop Res, 2003. 21(1): p. 110-6.
75. Carver, S.E. and C.A. Heath, Increasing extracellular matrix production in regenerating cartilage with intermittent physiological pressure. Biotechnology and Bioengineering, 1999. 62(2): p. 166-174.
76. Hu, J.C. and K.A. Athanasiou, The effects of intermittent hydrostatic pressure on self-assembled articular cartilage constructs. Tissue Eng, 2006. 12(5): p. 1337-44.
77. Elder, B.D. and K.A. Athanasiou, Effects of confinement on the mechanical properties of self-assembled articular cartilage constructs in the direction orthogonal to the confinement surface. Journal of Orthopaedic Research, 2008. 26(2): p. 238-246.
78. Jortikka, M.O., et al., The role of microtubules in the regulation of proteoglycan synthesis in chondrocytes under hydrostatic pressure. Arch Biochem Biophys, 2000. 374(2): p. 172-80.
79. Liang, S., et al., Hydrodynamic shear rate regulates melanoma-leukocyte aggregation, melanoma adhesion to the endothelium, and subsequent extravasation. Ann Biomed Eng, 2008. 36(4): p. 661-71.
80. Croll, T.I., et al., A blank slate? Layer-by-layer deposition of hyaluronic acid and chitosan onto various surfaces. Biomacromolecules, 2006. 7(5): p. 1610-22.
81. Spiteri, C.G., R.M. Pilliar, and R.A. Kandel, Substrate porosity enhances chondrocyte attachment, spreading, and cartilage tissue formation in vitro. Journal of Biomedical Materials Research Part A, 2006. 78A(4): p. 676-683.
82. Al-Munajjed, A.A., et al., Influence of pore size on tensile strength, permeability and porosity of hyaluronan-collagen scaffolds. J Mater Sci Mater Med, 2008. 19(8): p. 2859-64.
83. Tigli, R.S. and M. Gumusderelioglu, Chondrogenesis on BMP-6 loaded chitosan scaffolds in stationary and dynamic cultures. Biotechnol Bioeng, 2009. 104(3): p. 601-10.
84. Zhao, J., et al., Improving mechanical and biological properties of macroporous HA scaffolds through composite coatings. Colloids Surf B Biointerfaces, 2009. 74(1): p. 159-66.
85. Yoshioka, T., et al., In vitro evaluation of biodegradation of poly(lactic-co-glycolic acid) sponges. Biomaterials, 2008. 29(24-25): p. 3438-3443.
86. Langer, R. and J.P. Vacanti, Tissue Engineering. Science, 1993. 260(5110): p. 920-926.
87. Freed, L.E., et al., Neocartilage formation in vitro and in vivo using cells cultured on synthetic biodegradable polymers. J Biomed Mater Res, 1993. 27(1): p. 11-23.
88. Park, T.G., Degradation of Poly(Lactic-Co-Glycolic Acid) Microspheres - Effect of Copolymer Composition. Biomaterials, 1995. 16(15): p. 1123-1130.
89. Loo, S.C.J., et al., Effect of isothermal annealing on the hydrolytic degradation rate of poly(lactide-co-glycolide) (PLGA). Biomaterials, 2005. 26(16): p. 2827-2833.
90. Zhang, Z.H., et al., Efficient hydrolysis of chitosan in ionic liquids. Carbohydrate Polymers, 2009. 78(4): p. 685-689.
91. Hezi-Yamit, A., et al., Impact of polymer hydrophilicity on biocompatibility: implication for DES polymer design. J Biomed Mater Res A, 2009. 90(1): p. 133-41.
92. Lee, C.T. and Y.D. Lee, Preparation of porous biodegradable poly(lactide-co-glycolide)/hyaluronic acid blend scaffolds: Characterization, in vitro cells culture and degradation behaviors. Journal of Materials Science-Materials in Medicine, 2006. 17(12): p. 1411-1420.
93. Han, Y., et al., Cartilage regeneration using adipose-derived stem cells and the controlled-released hybrid microspheres. Joint Bone Spine. 77(1): p. 27-31.
94. Clark, A.L., et al., In situ chondrocyte deformation with physiological compression of the feline patellofemoral joint. Journal of Biomechanics, 2003. 36(4): p. 553-568.
95. Tan, H., et al., Gelatin/chitosan/hyaluronan ternary complex scaffold containing basic fibroblast growth factor for cartilage tissue engineering. J Mater Sci Mater Med, 2007. 18(10): p. 1961-8.
96. Moreira-Teixeira, L., et al., Chitosan-based hydrogels as extracellular matrix for cartilage tissue engineering: In vitro biological evaluation. Tissue Engineering Part A, 2008. 14(5): p. 711-711.
97. Madihally, S.V. and H.W.T. Matthew, Porous chitosan scaffolds for tissue engineering. Biomaterials, 1999. 20(12): p. 1133-1142.
98. Lao, L.H., et al., Chitosan modified poly(L-lactide) microspheres as cell microcarriers for cartilage tissue engineering. Colloids and Surfaces B-Biointerfaces, 2008. 66(2): p. 218-225.
99. Kim, C.H., et al., Chitosan scaffold as a structural base material for tissue engineering. Tissue Engineering Part A, 2008. 14(5): p. 821-822.
100. Barker, M.K. and B.B. Seedhom, The relationship of the compressive modulus of articular cartilage with its deformation response to cyclic loading: does cartilage optimize its modulus so as to minimize the strains arising in it due to the prevalent loading regime? Rheumatology (Oxford), 2001. 40(3): p. 274-84.
101. Chen, W.Y.J. and G. Abatangelo, Functions of hyaluronan in wound repair. Wound Repair and Regeneration, 1999. 7(2): p. 79-89.
102. Akmal, M., et al., The effects of hyaluronic acid on articular chondrocytes. J Bone Joint Surg Br, 2005. 87(8): p. 1143-9.
103. Seedhom, Z.J.L.a.B.B., Light and low-frequency pulsatile hydrostatic pressure
enhances extracellular matrix formation by bone marrow mesenchymal cells: an in-vitro study with special reference to cartilage repair. J. Engineering in Medicine, 2007. 221: p. 499-507.
104. Huang, A.H., et al., Long-term dynamic loading improves the mechanical properties of chondrogenic mesenchymal stem cell-laden hydrogel. Eur Cell Mater. 19: p. 72-85.
105. Appelman, T.P., et al., The differential effect of scaffold composition and architecture on chondrocyte response to mechanical stimulation. Biomaterials, 2009. 30(4): p. 518-25.
106. Blanco, F.J., et al., Chondrocyte apoptosis induced by nitric oxide. Am J Pathol, 1995. 146(1): p. 75-85.
107. Hashimoto, S., et al., Linkage of chondrocyte apoptosis and cartilage degradation in human osteoarthritis. Arthritis Rheum, 1998. 41(9): p. 1632-8.
108. Hashimoto, S., et al., Chondrocyte apoptosis and nitric oxide production during experimentally induced osteoarthritis. Arthritis Rheum, 1998. 41(7): p. 1266-74.
109. Kuhn, K., et al., Cell death in cartilage. Osteoarthritis Cartilage, 2004. 12(1): p. 1-16.
110. Abramson, S.B., et al., The role of nitric oxide in tissue destruction. Best Pract Res Clin Rheumatol, 2001. 15(5): p. 831-45.
111. Studer, R.K., et al., Nitric oxide inhibits chondrocyte response to IGF-I: inhibition of IGF-IRbeta tyrosine phosphorylation. Am J Physiol Cell Physiol, 2000. 279(4): p. C961-9.
112. Amin, A.R. and S.B. Abramson, The role of nitric oxide in articular cartilage breakdown in osteoarthritis. Curr Opin Rheumatol, 1998. 10(3): p. 263-8.
113. Hsu, S.H., et al., The effect of two different bioreactors on the neocartilage formation in type II collagen modified polyester scaffolds seeded with chondrocytes. Artif Organs, 2005. 29(6): p. 467-74.
114. Lee, D.A., et al., Response of chondrocyte subpopulations cultured within unloaded and loaded agarose. Journal of Orthopaedic Research, 1998. 16(6): p. 726-733.
115. Maneiro, E., et al., The biological action of hyaluronan on human osteoartritic articular chondrocytes: the importance of molecular weight. Clin Exp Rheumatol, 2004. 22(3): p. 307-12.
116. Mizuno, S., et al., Hydrostatic fluid pressure enhances matrix synthesis and accumulation by bovine chondrocytes in three-dimensional culture. Journal of Cellular Physiology, 2002. 193(3): p. 319-327.
117. Angele, P., et al., Cyclic hydrostatic pressure enhances the chondrogenic phenotype of human mesenchymal progenitor cells differentiated in vitro. J Orthop Res, 2003. 21(3): p. 451-7.
118. Davisson, T., R.L. Sah, and A. Ratcliffe, Perfusion increases cell content and matrix synthesis in chondrocyte three-dimensional cultures. Tissue Engineering, 2002. 8(5): p. 807-816.
119. Nicodemus, G.D. and S.J. Bryant, Mechanical loading regimes affect the anabolic and catabolic activities by chondrocytes encapsulated in PEG hydrogels. Osteoarthritis and Cartilage, 2010. 18(1): p. 126-137.
120. De Croos, J.N.A., et al., Cyclic compressive mechanical stimulation induces sequential catabolic and anabolic gene changes in chondrocytes resulting in increased extracellular matrix accumulation. Matrix Biology, 2006. 25(6): p. 323-331.
121. Benya, P.D. and J.D. Shaffer, Dedifferentiated chondrocytes reexpress the differentiated collagen phenotype when cultured in agarose gels. Cell, 1982. 30(1): p. 215-24.
122. Risbud, M., et al., In vitro expression of cartilage-specific markers by chondrocytes on a biocompatible hydrogel: implications for engineering cartilage tissue. Cell Transplant, 2001. 10(8): p. 755-63.
123. Ofek, G. and K.A. Athanasiou, Micromechanical properties of chondrocytes and chondrons: Relevance to articular cartilage tissue engineering. Journal of Mechanics of Materials and Structures, 2007. 2(6): p. 1059-1086.