Hyaline Cartilage Regeneration Using Mixed Human Chondrocytes and Transforming Growth Factor-β1-Producing Chondrocytes
SUN U. SONG, Ph.D.,1 YOUNG-DEOG CHA, M.D.,1 JEOUNG-UK HAN, M.D.,1
IN-SUK OH, M.D.,2 KYOUNG BAEK CHOI, M.S.,3 YOUNGSUK YI, Ph.D.,3
JONG-PIL HYUN, B.S.,3 HYEON-YOUL LEE, B.S.,3 GUANG FAN CHI, Ph.D.,3
CHAE-LYUL LIM, M.S.,3 J. KELLY GANJEI, B.S.,4 MOON-JONG NOH, Ph.D.,4
SEONG-JIN KIM, Ph.D.,5 DUG KEUN LEE, Ph.D.,4 and KWAN HEE LEE, M.D.1,3,4
1Clinical Research Center, College of Medicine, Inha University, Inchon, South Korea.
2Department of Orthopedic Surgery, College of Medicine, Inha University, Inchon, South Korea.
3TissueGene Asia, Inchon, South Korea.
4TissueGene, Gaithersburg, Maryland.
5Laboratory of Cell Regulation and Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
Address:
http://www.liebertonline.com/doi/abs/10.1089/ten.2005.11.1516
Summary
This goal of this study was to compare a mixture of transforming growth factor-β1 (TGF- β1)-producing human chondrocytes and primary human chondrocytes (hChon) in terms of cartilage regeneration with either hChon-TGF- β1 or hChon cells alone. This was to be studied in the context of hyaline articular cartilage, which has a very limited regenerative capacity and does not heal well after traumatic injury or other defects. Several other proposed methods for regenerating articular cartilage including use of mesenchymal stem cells have shown some promise but also several disadvantages.
Histological and immunohistochemical staining of new tissue in both mice and rabbits show that the mixture of transduced and untransduced chondrocytes has higher efficacy in regenerating hyaline cartilage than only transduced cells. This may be because the untransduced chondrocytes serve as additional bulk material to fill the defect and can be targeted by TGF- β1 produced by transduced cells. While this study shows the effects of TGF- β1 on chondrocyte differentiation the exact molecular mechanism that controls cartilage repair is still unknown.
Significance
Osteoarthritis is caused by erosion of the articular cartilage around a joint, which is primarily composed of hyaline cartilage. It is often treated by total joint replacements, which have short lifespans and can cause biomechanical and immune responses in the host. This paper suggests a method that could lead to autografts that would enable patients to quickly regenerate lost hyaline cartilage, which would provide an alternative method of treatment.
Submitted by Chris Han
7 comments:
Do non-transduced cells produce no TGF-beta1? 20ng/105 cells/24 hrs is stated as optimal for growth. If non-transduced cells do produce some TGF-beta1, how much is it lacking? Because retroviruses are so risky for clinical applications, can TGF-beta1 be exogenously introduced?
transduction leads to higher growth potential of the cells. but how do the condrocite cells translate into regenerated collagen? can this procedure work when there is no collagen to bond to? is condrocite cells filling the gaps a good result if the purpose is to regenerate collagen
Why did they use TGF-B1? Was it shown to exist to articular chondrocytes naturally? Since articular chondrocytes have such low regenerative potential, it could be that naturally they are just missing the appropriate growth factors that induce proliferation. A preliminary test should be to culture articular chondrocytes with various locally exogenous growth factors, ideally at high and low concentrations, to see which would induce the greatest growth rate.
There are also safer ways to introduce new genes to cells, like using zinc finger nucleases (ZFN). I am not too familiar with the mechanism but here is a paper my former genetics professor sent me about gene addition using ZFN: http://mcb.berkeley.edu/courses/mcb140/urnov/misc/ti.pdf. The longer the sequence to be inserted, the lower the frequency of successful insertion.
Alisa: Normal chondrocytes do not produce significant levels of TGF-beta. The amount needed for optimal growth is less than the amount produced by the transduced cells, as a mixed culture regenerated cartilage better than a culture of just transduced cells.
There are probably safer methods of introducing TGF-beta1, but the retroviral approach ensured that the cells had a consistent, continuous supply of TGF-beta1. In clinical use it may be better to use ZFN to transduce the cells or even supply the TGF-beta1 in the ECM.
Alan: Chondrocyte cells are responsible for producing the collagen and proteoglycan matrix that forms cartilage. Under normal conditions they can maintain homeostasis, but if there is a large defect through trauma regular chondrocytes do not regenerate cartilage fast enough. Because chondrocytes produce collagen this procedure works even if the cartilage has been worn down to the bone in the defect. The TGF-beta transduction simply increases the rate of collagen production so that the chondrocytes are able to fill the defect.
Hi Chris,
The research in this paper has exciting potential in that it can provide a more robust, natural recovery method of cartilage defects. However, has the relative strength of the regrown cartilage been measured or tested somehow? Does the repair promoted by transduced cells lead to cartilage as "good" as the original or are there imperfections/side effects? Does the paper go into this at all?
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