The Biomechanics Aspects of Cell Injections into the Brain

NEW modo 2016

The lab of McGowan Institute for Regenerative Medicine affiliated faculty member Michel Modo, PhD, Professor in the Department of Radiology at the University of Pittsburgh with secondary appointments in the Department of Bioengineering and the Center for Neural Basis of Cognition, recently published a paper in Scientific Reports that characterizes the biomechanics aspects of cell injections into the brain. Dr. Modo shares the paper with the regenerative medicine community as it conceptualizes the delivery of therapeutic products through a small-bore needle, an issue commonly neglected for these types of therapies. The abstract of the paper reads:

Intracerebral implantation of cell suspensions is finding its clinical translation with encouraging results in patients with stroke. However, the survival of cells in the brain remains poor. Although the biological potential of neural stem cells (NSCs) is widely documented, the biomechanical effects of delivering cells through a syringe-needle remain poorly understood. We here detailed the biomechanical forces (pressure, shear stress) that cells are exposed to during ejection through different sized needles (20G, 26G, 32G) and syringes (10, 50, 250 μL) at relevant flow rates (1, 5, 10 μL/min). A comparison of 3 vehicles, Phosphate Buffered Saline (PBS), Hypothermosol (HTS), and Pluronic, indicated that less viscous vehicles are favorable for suspension with a high cell volume fraction to minimize sedimentation. Higher suspension viscosity was associated with greater shear stress. Higher flow rates with viscous vehicle, such as HTS reduced viability by ~10% and also produced more apoptotic cells (28%). At 5 μL/min ejection using a 26G needle increased neuronal differentiation for PBS and HTS suspensions. These results reveal the biological impact of biomechanical forces in the cell delivery process. Appropriate engineering strategies can be considered to mitigate these effects to ensure the efficacious translation of this promising therapy.