Regenerative engineering for reconstruction of the knee anterior cruciate ligament (ACL) : a trial.

2005 Fiscal Year Final Research Report Summary

• Project/Area Number: 15591606
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Orthopaedic surgery
• Research Institution: The Jikei University School of Medicine
• Principal Investigator: MARUMO Keishi The Jikei University School of Medicine, Assistant Professor, 医学部, 助教授 (70199925)
• Co-Investigator(Kenkyū-buntansha): TSUJI Michiko The Jikei University School of Medicine, Lecturer, 医学部, 講師 (80207365) ; YOSHIDA Mamoru The Jikei University School of Medicine, Research Assistant, 医学部, 助手 (10266702) ; KUROSAKA Daizaburo The Jikei University School of Medicine, Research Assistant, 医学部, 助手 (80297382)
• Project Period (FY): 2003 – 2005
• Keywords: Regenerative engineering / ACL fibroblast cells / reconstructed ACL / ACL再建術

Research Abstract

From 1996, we have been performing ligament reconstructions for tears of the knee anterior cruciate ligament (ACL). Along with autograft tendons, biodegradable fibers made of poly-L-lactic acid used as augmentation devices (PL-LAD) have been applied. So far, there have been reports in the literature on low frequency of PL-LAD-related defects and good clinical outcomes of PL-LAD reconstructions. These reports together with results of histological studies of biopsy specimens collected from the reconstructed ligaments and results of collagen analyses clearly indicate that shortly after the reconstruction, the ligaments undergo structural changes that make them closely resemble the native ACL tissue.
In the present research, we plan to establish a clinically reliable method of ACL reconstruction using PL-LAD of sufficient tensile strength as an ACL scaffold for rebuilding of the ligament tissue.
Human ACL fibroblast cells were grown in a shaking culture on a soaked strip of PL-LAD (width 6mm, length 100mm, tensile strength at break 1180N, elongation at break 19%), pre-wet in the cell suspension of 10x1^7 cells/ml. Then, tensile traction (30 times/min, 50N) generated by a periodic extension stimulator was applied to the culture. Growth of fibroblasts attaching to the PL-LAD fibers and extending along them was observed. However, biochemical analyses of matrix content could not be performed because of inefficient matrix synthesis.
Next, in a rabbit experiment, PL-LAD was implanted subcutaneously for 3 weeks. The tissue was then removed, attached to the periodic extension stimulator and cultured for 10 days under the tensile traction (10 times/min,0-0.05 kg). Observations of the tissue under an optical microscope, biochemical analysis of collagen as well as comparative studies were carried out.
At present, a clear significant difference between the two tissues has not been observed. Further experiments with altered culture conditions and tensile traction forces are necessary.