Chimerism practices across Canadian transplant centres: review of current standards and variations

Background Chimerism analysis is used in hematopoietic stem cell transplantation (HSCT) to evaluate donor engraftment and assess underlying disease status. Practices vary greatly amongst Canadian transplant centres, and currently, there are no consensus guidelines for testing methodology, time points, cellular source and clinical interventions. Objectives To review the current chimerism practice patterns for Canadian transplant centres and review current literature Study design We surveyed members of Cell Therapy and Transplant Canada (CTTC) via a web based application regarding chimerism practices nationwide with approximately half of all transplant centres responding. Results The majority of centres used similar chimerism laboratory methodologies, though we identified key areas of heterogeneity across transplant centres, namely in the time points for testing and the cellular lineages evaluated. Implications and management of mixed donor chimerism also varied between centres resulting in variability of interventions. Conclusions Review of current chimerism testing literature highlighted the improving sensitivities of novel testing methods available as well as testing specific cellular lineages to evaluate ongoing donor hematopoiesis. Our survey emphasizes the importance of advocating for a national standard in chimerism testing, and subsequent management based on chimerism results, to better inform clinical practice and to aid in development of prospective research.