Motion increases cell length in tissue cultures

The elongated cell shape indicate that the cells are flourishing in their environment.

HOLLYWOOD, Fla. — Mechanical manipulation of fibroblast cells helps promote cell growth, a new experimental study shows. The finding may help researchers in the field of tissue engineering to develop viable future alternatives to allograft or autograft for ligament repair.

Using fibroblasts from mouse embryos, Seth C. Gamradt, MD, and researchers at the University of California — Los Angeles, School Of Medicine discovered that short-term motion led to the development of elongated cells that molded to scaffolding — a precursor to laying down the matrix of ligament tissue.

Gamradt presented the results of the study at the 2005 International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine Congress.

“The elongated shape shows that the cells are thriving in their environment,” he said.

The agitated fibroblasts also produced more actin and increased cytoskeleton production than stagnate controls. Agitated and stagnate cell groups did not differ significantly in cell densities, however.

Cell incubation

In the study, the researchers sterilized and covered six, 95% porous poly-L-lactic acid scaffolds with fibronection and placed 4 million NIH/3T3 mouse embryonic fibroblasts on each. Three samples each served as experimental and control groups, according to the study.

Both cell groups remained immobilized for 24 hours. The cell cultures were then placed within a custom bioreactor containing two cultivation chambers, which was then placed into a cell incubator at 5% carbon dioxide at 37°C. The experimental cells were then affixed onto pegs within the chambers to undergo 1% strain — delivered via cyclic, uniaxial stretching — and 0.125 Hz for a 24 hour period, according to the study.

To control for extraneous variables, investigators used several staining methods to verify seeding distribution, ensure cell centers remained covered, and confirm actin levels after examination, Gamradt noted.

Future directions

The study, supported by the Musculoskeletal Transplant Foundation, helps lay the foundation for future ligament tissue engineering, including investigations into gene expression and additional causes of germination, Gamradt said.

“The most important hurdle to overcome will be obtaining adequate biomechanical strength, as the native ACL has a tensile strength of 1730 N. Most studies of tissue ligament engineering have had difficulty attaining tissue of adequate mechanical strength,” he noted.

For more information:
McAllister DR, Puk B, Gamradt SC, et al. The effects of short term mechanical stimulation on fibroblasts cultured on synthetic scaffolds. #66. Presented at the 2005 International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine Congress. April 3-7, 2005. Hollywood, Fla.