He is the Dr. Donald and Ruth Weber Goodman Professor of Innovative Therapeutics at Case Western Reserve University School of Medicine.

As part of the National Institutes of Health Oxford-Cambridge Scholar Program, he earned a PhD in 2007.

[8] While a graduate student, Tesar published a paper describing epiblast-derived stem cells, a new type of pluripotent stem cell,[4] research for which he received both the Beddington Medal of the British Society for Developmental Biology[2] and the Harold M. Weintraub Award of the Fred Hutchinson Cancer Research Center.

[14][15] Tesar identified drugs that stimulate myelin regeneration and reverse paralysis in mice with multiple sclerosis.

[16] Tesar also identified CRISPR and antisense oligonucleotide therapeutics that restored myelination and extended the lifespan of mice with Pelizaeus–Merzbacher disease.