Timothy S. Olson, MD, PhD

Timothy S. Olson, MD, PhD, focuses on pediatric hematopoietic stem cell transplantation (HSCT), with a specific emphasis on HSCT for patients with inherited and acquired bone marrow failure.

Areas of Expertise: Blood and marrow transplantation, Bone marrow failure
Locations: Main Campus
Appointments and Referrals: 1-800-TRY-CHOP (1-800-879-2467)

  • Background

    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 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

    Medical School

    MD - University of Virginia School of Medicine, Charlottesville, VA


    Pediatrics - The Children's Hospital of Philadelphia, Philadelphia, PA


    Pediatric Hematology/Oncology - The Children's Hospital of Philadelphia, Philadelphia, PA

    Board Certification

    Pediatric Hematology-Oncology

    Graduate Degree

    PhD in Molecular Physiology - University of Virginia, Charlottesville, VA

  • Titles and Academic Titles

    Attending Physician

    Assistant Professor of Pediatrics, Perelman School of Medicine at The University of Pennsylvania

  • Departments and Services
  • Publications



    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.

    5. 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. 


    Olson T.S., Caselli A., Otsuru S., Hofmann T.J., Williams R., Paolucci P., Dominici, M., and Horwitz EM. (2013). Megakaryocytes Promote Murine Osteoblastic HSC Niche Expansion and Stem Cell Engraftment after Radioablative Conditioning. Blood. 121(26):5238-49. PMCID: PMC3695366.   

    Caselli A.*, Olson T.S.*, Otsuru S., Chen X., Hofmann T.J., Nah H-D., Paolucci P., Dominici M., and Horwitz E.M. (2013). IGF-1-Mediated Osteoblastic Niche Expansion Enhances Long-Term Hematopoietic Stem Cell Engraftment after Murine Bone Marrow Transplantation. Stem Cells Oct; 31(10):2193-204. *Shared first-authorship.

    Hartung H.D.*, Olson T.S.*, and Bessler, M. (2013). Acquired Bone Marrow Failure in Children.  Pediatr Clin North Am.  Dec; 60(6):1311-36.  PMCID: In Process.  Invited Review. *Shared first-authorship.  

    Otsuru S., Hofmann T.J., Olson T.S., Dominici M., and Horwitz E.M. (2013). Improved Isolation and Expansion of Bone Marrow Mesenchymal Stromal Cells Using a Novel Marrow Filter Device.  Cytotherapy, 15(2):146-53.  

    Marino R., Otsuro S., Hofmann,T.J., Olson T.S., Rasini V., Veronesi E., Boyd K., Gaber M.W., Martinez C., Paolucci P., Dominici M., and Horwitz E.M. (2013). Delayed Marrow Infusion in Mice Enhances Hematopoietic and Osteopoietic Engraftment by Facilitating Transient Expansion of the Osteoblastic Niche.  Biol Blood Marrow Transplant. Nov; 19(11): 1566-73.  

    Posters and Presentations


    TS Olson. New Directions in Bone Marrow Failure Symposium, Texas Children’s Cancer and Hematology Centers (Oral Presentation and Expert Panelist)

    TS Olson. Children’s Hospital of Philadelphia and University of Pennsylvania Normal and Malignant Hematopoiesis Retreat and Symposium. (Oral Presentation)


    TS Olson, A Caselli, S Otsuru, T Hofmann, and EM Horwitz. Enhancement of hematopoietic stem cell engraftment efficiency through upregulation of host megakaryocyte-driven endosteal stem cell niche expansion following radioablative conditioning [oral presentation]. The Future of Stem Cell Transplantation Meeting; 2012 Jan;  Atlanta, GA.

  • 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

  • Leaderships
    Memberships in Professional Organizations

    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
    2008-present, American Society of Pediatric Hematology/Oncology, Member 
    2009-present, American Board of Pediatrics Certification in General Pediatrics