Successful colonization of the testicular germinal epithelium by bone marrow stem cells producing spermatozoa of donor genotype is rare.

Abstract

Background: It is not known whether bone marrow stem cells when injected intravenously for a bone marrow transplant colonize the human testicular epithelium. No previous studies of sperm genotype after bone marrow transplantation are reported.

Objectives: To differentiate host from donor genotype in spermatozoa of men who have undergone successful bone marrow transplants.

Materials and methods: Triplet DNA samples (spermatozoa, blood, and hair) obtained from men who had recovered sperm production after bone marrow transplant were genotyped using 44 autosomal and three sex-related single nucleotide polymorphisms to determine the tissue genotype in pairwise comparisons of DNA profiles.

Results: Participants were 14 men at a median of 5.5 years after allogeneic bone marrow transplant who had a median sperm output of 77 million spermatozoa/ejaculate. In 14/14 the donor (leukocyte) DNA genotype differed significantly from the spermatozoa and hair genotypes whereas hair and sperm genotypes showed no variations.

Discussion: These data suggest that paternity after a successful bone marrow transplant is likely to be of the host and not the donor's genetic origins. The study's small sample size reflects the paucity of eligible man with recovered spermatogenesis after bone marrow transplant and represents preliminary evidence. A large-scale epidemiological analysis to estimate the frequency of bone marrow donor stem cell colonization of the testicular germinal epithelium based on progeny sex ratio and frequency of female donors is proposed.

Conclusion: Successful colonization of the testicular germinal and hair follicle epithelia by allogeneic bone marrow transplant donor stem cells is rare or does not occur.