MIGRATION TARGETED APPROACHES TO REGENERATION
Regenerative therapies have introduced stem and progenitor cells into the adult Nervous System to replace damaged neurons and regain motor and sensory functions. Despite enriched understanding of intrinsic cell differentiation processes, the impact of extrinsic signals on the integration of replacement cells remains incompletely understood. The Vaz lab has developed in vitro and ex vivo technology to direct transplanted cells to their targets using tunable external stimuli.
Stem-like cells introduced into the NS must navigate the complex and pre-existing architecture of adult tissue, which produces fundamentally distinct signals and cues than those of the developing NS. While BME technologies have been used to promote transplant viability1, our lab has examined how exogenous cues can mediate the navigation of replacement cells in situ. The Vaz Lab group developed microfluidic systems to measure progenitor migration in response to ligands released from injured retina that included electric fields. Our galvanotaxis microfluidic assay remains unique because it superimposes electrical and chemical fields across the cellular microenvironment, independently, and without altering the distribution of either field2. This engineering contribution was groundbreaking because our group became the first to apply combinatory electro-chemotactic fields to direct the migration of transplantable retinal progenitors3. Via our biotechnology approach, we demonstrated increased cell distances traveled and increased directionality of cell movement 3-5 times that of either field, individually. This specialized research was presented by invite at the International Gordon Conference in Microfluidics (Lucca, Italy) and at the World Congress of Biosensors (FL). Our unique approach to retinal regeneration using microfluidics has merited an additional independent funding award from NEI in 2020 (1R21 EY031439), and guest editor for a special 2021 issue of Micromachines entitled Microfluidics in the Nervous System.
We continue to expand our electro-chemotaxis strategy by developing ex vivo testing systems of whole-eye explants4. Results have demonstrated dramatic differences in the penetration of transplanted cells within eye mimics (alginate) to highlight the significance of adult retinal architecture in cell navigation. In addition, the Vaz Lab has further applied our microfluidic approach to VS repair by examining the neuroprotective migration of retinal Müller cells5. Our microfluidic studies illustrate unexpected chemo- and electrotaxis from these glia that have been cited commercially as technical references by the manufacturer, Kerafast.
Figure 3: Migration-targeted regeneration. (A) Image of explanted mouse eye used to produce (B) the microfluidic retina device that (C) creates tunable gradients at anatomical scale. (D) Our galvanotaxis assay applies electro-chemotactic (EC) stimuli to (E) increase the directionality and distances traveled by retina progenitors. (F) Our new ex vivo testing system applies EC stimuli across explanted eye for enriched integration. (G) Guest editor for special 2021 issue of Micromachines.
(i) Visual NS: We have begun to mechanistically examine electro-chemotactic migration by correlating activated receptor proteins with upregulated transcription factors. This NEI work is performed collaboratively with my Rutgers co-PI (Dr. L. Cai) using developmental mouse models and RNA-seq technology of retinal progenitors.
(ii) Peripheral NS: We also examine Schwann cell-mediated repair by developing hybrid microfluidic systems integrated with spinal cord explants. The work has measured differences in spinal cord outgrowth as a function of extracellular Schwann cell density and is examining the significance of cerebrospinal fluid to better mimic in vivo conditions. This research is performed in collaboration with Rutgers Neuroscience (Dr. B. Firestein) and is in preparation for a funding proposal to the New Jersey State commission for spinal cord research.
Selected References (Click for Pubmed Access):
Thakur A.; Mishra S.; Redenti S.; Majeska R.; Vazquez, M., ‘Formation and Adhesion of Retinal Neuroclusters within Substrates of Transplantable Biomaterials,’ J Tissue Eng. 2018 Jan 9;9.
Mishra S.; Vazquez, M., ‘A Gal-MµS device to evaluate cell migratory response to combined galvano-chemotactic fields,’ Biosensors (Basel). 2017 Nov 21;7(4).
Vazquez, M., 'Electro-chemotactic stimuli for cell replacement therapy in neurosensory retina,' Neural Regen Res. 2020 Mar;15(3):450-452.
Mut, S.; Mishra, S.; Pena J.; Vazquez, M. An Ex Vivo Eye Facsimile System (EVES) to evaluate transplantation strategies for cell replacement therapy, The Association for Research in Vision and Ophthalmology (ARVO 2020, Baltimore, MD), Gene and Stem Cell Therapy, Poster Platform 795-B0347.
Pena J.; Dulger N.; Redenti, S.; Majeska R.; and Vazquez, M., ‘Controlled microenvironments to evaluate chemotactic properties of cultured Muller glia,' Exp Eye Res. 2018 Aug;173:129-137.