Citation

Biomaterials have shown promise for treatment of injuries to the nervous system. Laminin, a glycoprotein, forms distinct polymers under neutral (pH 7; neutral laminin, nLam) or acidic (pH 4; acidic laminin, aLam) conditions (1, 2). aLam promotes significant axonal growth (2), making it of interest as a therapeutic for nervous tissue injuries.
In this thesis, instead of as a substrate, we evaluate unbound aLam. In Chapter 2.1, we use an in vitro model system to investigate the mechanisms underlying aLam growth promotion. Results indicate: 1) laminin can act as a signaling molecule promoting outgrowth of adult neurons in vitro; 2) aLam is a more efficient promoter of outgrowth than nLam; 3) both polymers signal through α1 and α3 integrins without increasing their expression; 4) aLam, increases α3 integrins when α1 integrins are blocked; 6) aLam increases vinculin, a focal adhesion complex protein. These findings indicate that aLam promotes outgrowth by increasing integrin activation to enhance neurite outgrowth.
In Chapter 2.2 microcontact printing and live imaging were combined to evaluate aLam’s effects on growth dynamics. Our results suggest: 1) neurons will adhere to stamps and grow in a directional manner in culture; 2) cells did not adhere or grow well during live imaging. Results indicate potential for directing neuronal outgrowth, but optimization is necessary to assess growth dynamics.
Peripheral nerve injury (PNI) and spinal cord injury (SCI) are devastating. In Chapter 3.1 we investigate aLam’s treatment potential in PNI. Results indicate that aLam treatment: 1) increased presence of larger diameter axons; 2) facilitated compliance in treadmill walking; 3) alleviated autophagia; 4) did not affect motor function, axon number or myelination. These data show that aLam treatment elicits an axon growth response without affecting motor function recovery. Further research is needed to optimize treatment for functional improvements.
Chapter 3.2 evaluates aLam treatment after SCI. Results show that aLam treatment: 1) did not affect axon regeneration; 2) decreased astrocyte activation; 3) did not affect neuropathic pain or motor outcomes. The data indicate treatment did not lead to functional improvements. Further research is needed to investigate the potential of aLam for SCI repair.