Pretransplant Parathyroid Hormone Level Has No Correlation with Platelet Recovery After Stem Cell

Stem cell fate is influenced by specialized microenvironments called as stem cell niche. Osteoblasts are considerd to play very important role in stem cell niche. They are activated by parathyroid hormone (PTH) or PTH related protein through PTH/PTHrP receptor and produce hematopoietic growth factors. In few large animal studies PTH treatment after hematopoietic stem cell transplantation (HSCT) improved post-transplant platelet count and CD4 lymphocyte count. Effect of PTH on cord blood stem cell transplantation to improve engraftment is under clinical trial. Therefore, authors investigated on correlation between pre-transplant serum PTH level and platelet recovery after allogeneic HSCT.

From January 2008 to December 2009, we measured pre-transplant serum PTH, ferritin of 28 patients who underwent allogeneic HSCT. Post-transplant platelet was checked at the point of post-transplant 14 days, 30 days, 60 days, 90 days and 180days. Surveillance of cytomegalovirus was done by weekly or biweekly CMV-PCR assay. Acute graft-versus-host disease (GVHD) was graded by IBMTR classification and chronic GVHD by NIH scoring system.

Five patients received graft from partially matched donors and the others from fully matched donors, 15 from unrelated and 13 from related donors. Nineteen patients were in high risk at diagnosis. Nonmyeloablative conditioning was applied to 7 patients. Only 1 patient used bone marrow as stem cell source. Median dose of infused stem cell was 5.7×10^∧6/kg (range 1.68 – 12.74). All patients were successfully engrafted. Acute GVHD more than grade 2 occurred in 15, and chronic GVHD more than moderate degree in 7. Five patients relapsed and 15 patients died of relapse or treatment related mortality. Pre-transplant serum PTH had no correlation with platelet count recovery. There was no correlation with pre-HSCT PTH and acute or chronic GVHD. However patient with lower PTH level had tendency to more frequent CMV reactivation (P=0.098).

Our hypothesis was that higher pre-transplant PTH would be related to better platelet recovery but failed to find correlation between two of them. There are various factors which affect engraftment and graft function. Role of PTH for engraftment should be evaluated in larger number of cases.

No relevant conflicts of interest to declare.