Advanced bioreactors are essential for meeting the complex requirements of in vitro
engineering functional skeletal tissues. To address this need, we have developed a computer
controlled bench-top bioreactor system with capability to apply complex concurrent
mechanical strains to three-dimensional matrices independently housed in 24 reactor
vessels, in conjunction with enhanced environmental and fluidic control. We demonstrate
the potential of this new system to address needs in tissue engineering, specifically toward
the development of a tissue engineered anterior cruciate ligament from human bonemarrow
stromal cells (hBMSC), where complex mechanical and biochemical environment
control is essential to tissue function. Well-controlled mechanical strains (resolution of
,0.1 mm for translational and ,0.1° for rotational strain) and dissolved oxygen tension
(between 0%–95%61%! could be applied to the developing tissue, while maintaining
temperature at 371/20.2°C about developing tissue over prolonged periods of operation.
A total of 48 reactor vessels containing cell culture medium and silk fiber matrices
were run for up to 21 days under 90° rotational and 2 mm translational deformations at
0.0167 Hz with only one succumbing to contamination due to a leak at an medium outlet
port. Twenty-four silk fiber matrices seeded with human bone marrow stromal cells
(hBMSCs) housed within reactor vessels were maintained at constant temperature
~ 371/20.2°C!, pH ~ 7.41/20.02! , and pO2 ~ 201/20.5%! over 14 days in culture.
The system supported cell spreading and growth on the silk fiber matrices based on SEM
characterization, as well as the differentiation of the cells into ligament-like cells and
tissue