My clinical efforts focus on pediatric hematopoietic stem cell transplantation (HSCT), with a specific emphasis on HSCT for patients with inherited and acquired bone marrow failure. Through my combined clinical activities in the Bone Marrow Failure Center within the Division of Hematology and the Blood and Marrow Transplant Section within the Division of Oncology, my goal is to facilitate outstanding care for patients with inherited bone marrow failure and acquired aplastic anemia during their transition from diagnostic evaluation to treatment through HSCT.
In coordination with these clinical efforts, my clinical research program seeks to retrospectively and prospectively assess outcomes for patients undergoing HSCT due to inherited and acquired bone marrow failure syndromes, defined and stratified by distinct cytogenetic abnormalities. Our ultimate goal is to develop targeted clinical trials which will serve to define optimal treatment strategies for patients with distinct genetic and immunologic etiologies of bone marrow failure.
The goal of my laboratory research program is to improve HSCT outcomes by identifying methods to decrease the incidence of graft failure following HSCT, which is a particularly critical challenge in the setting of transplant for non-malignant conditions such as bone marrow failure. We are specifically examining methods to enhance donor hematopoietic stem cell (HSC) engraftment efficiency following HSCT through enhancement of the functions of specialized areas of the bone marrow microenvironment, known as hematopoietic stem cell niches. We are currently testing therapeutic strategies that can be applied to enhance niche activity and receptivity for donor stem cells, which could be utilized to improve donor engraftment efficiency following clinical HSCT.
Education and Training
MD - University of Virginia School of Medicine, Charlottesville, VA
Pediatrics - The Children's Hospital of Philadelphia, Philadelphia, PA
Pediatrics - The Children's Hospital of Philadelphia, Philadelphia, PA
Pediatric Hematology/Oncology - The Children's Hospital of Philadelphia, Philadelphia, PA
PhD in Molecular Physiology - University of Virginia, Charlottesville, VA
Titles and Academic Titles
Medical Director, Blood and Marrow Transplant Program
Director of Research, Comprehensive Bone Marrow Failure Center
Assistant Professor of Pediatrics, Perelman School of Medicine at The University of Pennsylvania
Kamio, T., Gu B-W., Olson T.S., Zhang Y., Mason P.J., and Bessler, M. (2016) Mice with a mutation in the Mdm2 gene that interferes with MDM2/ribosomal protein binding develop a defect in erythropoiesis. PLoS One. 2016 Apr 4;11(4):e0152263. doi: 10.1371/journal.pone.0152263. eCollection 2016.
Betensky M., Babushok D., Roth J.J., Mason P.J., Biegel J.A., Busse T.M., Li Y., Lind C., Papazoglou A., Monos D., Podsakoff G., Bessler M., and Olson T.S. (2016) Clonal Evolution and Clinical Significance of Copy Number Neutral Loss of Heterozygosity of Chromosome Arm 6p in Acquired Aplastic Anemia. Cancer Genet. 209(1-2):1-10. PMCID PMC4738084.
Babushok D.V., Grignon A.L., Li Y., Atienza J., Xie H.M., Lam H-S., Hartung H., Bessler M., and Olson T.S. (2016) Disrupted lymphocyte homeostasis in hepatitis-associated acquired aplastic anemia is associated with short telomeres. Am J Hematol 91(2) 243-7. PMCID PMC4724330.
Babushok, D.V., Stanley N., Xie H.M., Huang H., Bagg A., Olson T.S., and Bessler M. (2016) Clonal Replacement Underlies Spontaneous Remission in Paroxysmal Nocturnal Haemoglobinuria. Br J Haematol 2016 Feb 23 [Epub ahead of Print] PMID: 26913981.
Babushok, D.V., Bessler M., and Olson T.S. (2016) Genetic predisposition to myelodysplastic syndrome and acute myeloid leukemia in children and young adults. Leuk Lymphoma. 57(3): 520-36. PMCID: PMC4798888.
Babushok D.V., Perdigones N., Perin J.C., Olson T.S., Ye W., Roth J.J., Lind C., Cattier C., Li Y., Hartung H., Paessler M.E., Frank D.M., Xie H.M., Cross S., Cockroft J.D., Podsakoff G.M., Monos D., Biegel J.A., Mason P.J., and Bessler M. : Emergence of Clonal Hematopoiesis in the Majority of Patients with Acquired Aplastic Anemia. Cancer Genet 208(4): 115-28, Apr 2015.
Otsuru S., Hofmann T.J., Raman P., Olson T.S., Guess A.J., Dominici M., and Horwitz E.M. : Genomic and Functional Comparison of Mesenchymal Stromal Cells Prepared Using Two Isolation Methods. Cytotherapy 17(3): 262-70, Mar 2015.
Olson T.S., Chan E.S., Paessler M.E., Sullivan K.E., Frantz, C.N., Russo, P. and Bessler, M. (2014). Liver Failure Due to Hepatic Angiosarcoma in an Adolescent with Dyskeratosis Congenita. J Pediatr Hematol Oncol May; 36(4):312-15. PMCID: PMC3714320
Oshrine B.R., Olson T.S., and Bunin N. (2014) Mixed chimerism and graft loss in pediatric recipients of an alemtuzumab-based reduced-intensity conditioning regimen for nonmalignant disease. Ped Blood Cancer 2014 Jun 17 [Epub ahead of print] PMID24939325
Olson T.S., Reiss U.M., Rogers Z.R., Sieff C., Vlachos A., Walkovich K., Wang W., and Shimamura A. (2014). Diagnosis and Treatment of Pediatric Acquired Aplastic Anemia (AAA): An Initial Survey of the North American Pediatric Aplastic Anemia Consortium (NAPAAC). Pediatr Blood Cancer. 2014 May;61(5):869-74. doi: 10.1002/pbc.24875. Epub 2013 Nov 27.
Babushok D.V., Xie H.M., Roth J.J., Perdigones N., Olson T.S., Cockroft J.D., Gai X., Perin J.C., Li Y., Paessler M.E., Hakonarson H., Podsakoff G.M., Mason P.J., Biegel J.A., and Bessler M. (2014). Single Nucleotide Polymorphism Array Analysis of Bone Marrow Failure Patients Reveals Characteristic Patters of Genetic Changes. Br. J. Hematol. Jan; 164(1):73-82.
Oshrine B.R., Olson T.S., and Bunin N. (2014) Mixed chimerism and graft loss in pediatric recipients of an alemtuzumab-based reduced-intensity conditioning regimen for nonmalignant disease. Pediatr Blood Cancer. Oct; 61 (1): 1852-9. PMID: 24939325.
Olson T.S., Chan E.S., Paessler M.E., Sullivan K.E., Frantz, C.N., Russo, P. and Bessler, M. (2014). Liver Failure Due to Hepatic Angiosarcoma in an Adolescent with Dyskeratosis Congenita. J Pediatr Hematol Oncol May; 36(4):312-15. PMCID: PMC3714320.
Williams D.A., Bennett C.A., Bertuch A., Bessler M., Coates T., Corey S., Dror Y., Huang J., Lipton J., Olson T.S., Reiss U.M., Rogers Z.R., Sieff C., Vlachos A., Walkovich K., Wang W., and Shimamura A. (2014). Diagnosis and Treatment of Pediatric Acquired Aplastic Anemia (AAA): An Initial Survey of the North American Pediatric Aplastic Anemia Consortium (NAPAAC). Ped Blood Cancer. May; 61(5):869-74. PMCID: PMC4280184.
Hartung H., Babushok D., Perdigones N., Perin J.C., Roth J., Olson T.S., Biegel J.A., Paessler M.E., Mason, P.J., and Bessler, M. : Towards Precision Medicine in Acquired and Inherited Bone Marrow Failure Syndromes. American Academy of Pediatrics National Conference, San Diego, CA 2014.
Posters and Presentations
Kwiatkowski J, Walters M, Locatelli F, Lal A, Evangelia Y, Kulozik A, Sauer M, Porter J, Thuret I, Hongeng S, Thrasher A, Olson TS, Schneiderman J, Elliot H, Tao G, Liu W, Colvin R, and Thompson A: LENTIGLOBIN GENE THERAPY IN PEDIATRICS, ADOLESCENTS, ADULTS WITHTRANSFUSION-DEPENDENT Β-THALASSEMIA American Society of Pediatric Hematology Oncology Annual Meeting Program (Abstract Published, meeting cancelled due to COVID-19) May 2020.
Oved J.H., Wang Y., Barrett D.M., Levy E.M., Huang Y., Monos D.S., Grupp S.A., Bunin N.J., and Olson T.S.: CD3+/CD19+ depleted matched and mismatched unrelated donor hematopoietic stem cell transplant with targeted T cell addback is associated with excellent outcomes in pediatric patients with non-malignant hematologic disorders Biol Blood Marrow Transplant 25(3): 549-555, Mar 2019.
Elgarten C.W., Myers R.M., Levy E., Freedman J.L., Bunin N.J., Fisher B.T., and Olson T.S.: Cytomegalovirus Reactivation in Children with Hemoglobinopathies Who Undergo Hematopoietic Cell Transplantation with Distal Alemtuzumab. American Society of Transplant and Cellular Therapy (TCT) 2019 Annual Meeting (Poster Presentation), Houston, TX 25(3): S309-S310, Feb 2019.
Oved J., Wang Y., Huang Y., Monos D., Barrett D., Grupp S.A., Bunin N., and Olson T.: Outcomes of Unrelated Donor Peripheral Stem Cell Transplantation For Patients with Non-Malignant Hematologic Disorders Using Two Partial T cell Depletion Strategies. American Society of Pediatric Hematology Oncology (ASPHO) 2018 Annual Meeting (Oral Presentation by Oved), Pittsburgh, PA May 2018.
Betensky M., Babushok D., Roth J.J., Mason P.J., Biegel J.A., Lind C., Monos D., Bessler M., and Olson T.S. : Copy Number Neutral Loss of Heterozygosity of Chromosome Arm 6p in Acquired Aplastic Anemia: Frequency, Clonal Evolution and Clinical Significance. Annual Meeting of the American Society of Pediatric Hematology/Oncology , Phoenix, AZ (Oral Presentation) May 2015.
Roth J.J., Babushok D.V., Perdigones, N., Olson T.S., Hartung, H.D., Cockroft, J.D., Pamu, S., Paessler M.E., Mason P.J., Bessler M., Wilmoth, D.M., Biegel J.A.: Utility of single nucleotide polymorphism arrays for patients with bone marrow failure. Presentation at The American Cytogenetics Conference, Asheville, NC 2014.
Olson T.S., Otsuru S., Hofmann T.J., Dominici M., and Horwitz E.M.: Expansion of the Endosteal Hematopoietic Stem Cell Niche Following Myeloablative and Reduced Intensity Conditioning Is Triggered By Hematopoietic Cell Loss. Annual Meeting of the American Society of Hematology, San Francisco, CA (Poster Presentation) Dec 2014.
Betensky M., Babushok D., Roth J.J., Mason P.J., Biegel J.A., Lind C., Monos D., Bessler M., and Olson T.S. : Clonal Evolution and Clinical Significance of Copy Number Neutral Loss of Heterozygosity of Chromosome Arm 6p in Acquired Aplastic Anemia Annual Meeting of the American Society of Hematology, San Francisco, CA (Poster Presentation) Dec 2014.
Oshrine, B., Olson T.S., and Bunin, N.: Mixed Chimerism and Graft Loss in Pediatric Recipients of an Alemtuzumab-Based Reduced-Intensity Conditioning Regimen for Nonmalignant Disease. Annual Meeting of the American Society of Bone Marrow Transplantation, Grapevine, TX. (Oral Presentation) Feb 2014.
Feb, 2019 "Partial T Cell Depletion Using CliniMACS for Unrelated Donor Peripheral Stem Cell Transplantation in Children with Non-Malignant Hematologic Diseases", Product Theater Miltenyi Biotec at TCT2019, Houston, TX
May, 2019 "Lentiglobin Gene Therapy in Transfusion-Dependent Beta-Thalassemia Patients with Non-β0/β0 Genotypes", American Society of Pediatric Hematology/Oncology 2019 Annual Meeting (Plenary Oral Presentation by Dr. Olson), New Orleans, LA
Jun, 2018 "Frontiers in Cellular Therapy for Sickle Cell Disease and Thalassemia Major", at Advances in Cellular Immunotherapy and Stem Cell Transplantation Conference, Children's Hospital of Philadelphia, Philadelphia, PA (regional audience)
Feb, 2017 "Curative Therapies for Patients with Non-Malignant Blood Cell Disorders" Seha International Paediatric Conference Abu Dhabi, UAE
Apr, 2017 "Curative Therapy for Sickle Cell Disease, Focus on Hematopoietic Stem Cell Transplantation", Goryeb Children's Hospital, Morristown Medical Center, Morrsitown, NJ Medical Center, Morrsitown, NJ
Jun, 2017 "Curative Cell Therapy Options for Sickle Cell Disease and Thalassemia Major", Robert Wood Johnson University Hospital, New Brunswick, N.J.
Jul, 2017 "Curative Therapy for Sickle Cell Disease and Beta Thalassemia Major", Pottstown Department of Pediatrics Grand Rounds, Pottstown, PA
Oct, 2017 "Curative Cellular Therapies for the Treatment of Sickle Cell Disease and Beta Thalassemia", Newark Beth Israel Pediatric Grand Rounds, RWJ Barnabas Health, Newark, NJ
Apr, 2016 "Hematopoietic Stem Cell Transplantation for Severe Thalassemia: Challenges and Opportunities", Webinar for The Mid-Atlantic Region Thalassemia Care Consortium. Philadelphia, PA
Jun, 2016 "Bone Marrow Failure and HSCT for Non-malignant Hematologic Disease at CHOP", Hematologic Malignancies Annual Joint Retreat. Children's Hospital of Philadelphia and University of Pennsylvania Abramson Cancer Center. Philadelphia, PA (regional audience)
Aug, 2016 "Hematopoietic Stem Cell Transplantation for Non-malignant Hematologic and Immunologic Diseases", Annual Meeting of The American Society for Clinical Laboratory Science, Philadelphia, PA
Sep, 2015 "Hematopoietic Stem Cell Transplantation for Sickle Cell Disease", Town Hall Meeting for families of children with sickle cell disease. Hosted by The Children's Hospital of Philadelphia Comprehensive Sickle Cell Center, Philadelphia, PA (regional audience)
"Bone Marrow Failure and Transplant" - 2015 Regional Conference of the Association of Pediatric Hematology/ Oncology Nurses, Villanova, PA.
"Pediatric-Adult Transition for Patients with Dyskeratosis Congenita" - DC Outreach Camp and Educational Meeting for Patients with Dyskeratosis Congenita and their Families, Camp Sunshine, Portland, ME.
"Pediatric-Adult Transition for Patients with Telomeropathies" - Inaugural Meeting of the Clinical Care Consortium of Telomere-Associated Ailments, Chicago, IL.
Awards and Honors
2014, American Society of Hematology Scholar Award
2013, Alexandra J. Kefalides Memorial Prize for Research in Normal and Malignant Hematopoiesis
2012, The Penn/CHOP Institute of Translational Medicine and Therapeutics and Clinical and Translational Research Center Junior Investigator Pilot Grant Program Awardee
2012, The Children’s Hospital of Philadelphia Poster Day Top Abstract Prize
2012, American Society of Bone Marrow Transplantation Travel Grant Awardee
2011-2013, Canuso Foundation Innovation Grant Award
2011, American Society of Hematology Research Training Award for Fellows
2011, American Society of Pediatric Hematology/Oncology Young Investigator Travel Award
2004, Michael J. Peach Outstanding Graduate Student in Health Sciences Finalist
2004, Robert M. Berne Outstanding Trainee in Cardiovascular Research Award
2002-2004, Cardiovascular Training Grant Fellowship, University of Virginia
2000-2002, Medical Scientist Training Grant Fellowship, University of Virginia
1998-2006, Dean’s Fellowship, University of Virginia
Editorial and Academic Positions
2015-present, Pediatric Transplantation
2013-present, Journal of Pediatric Hematology and Oncology
2013-present, Clinical Medicine Insights: Case Reports
2012-present, Biology of Blood and Marrow Transplantation
Leadership and Memberships
Memberships in Professional Organizations
2014-present, Clinical Care Consortium of Telomere-Associated Ailments
2012-present, North American Pediatric Aplastic Anemia Consortium
2008-present, Children's Oncology Group
2012-present, North American Pediatric Aplastic Anemia Consortium Member
2011-present, American Society of Bone Marrow Transplant, Member
2008-present, American Society of Hematology, Member
Patient Experience Ratings
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