A feasibility study on the prediction of acute graft-vs.-host disease before hematopoietic stem cell transplantation based on fetomaternal tolerance

Comparison of the clinical outcomes between NIMA-mismatched and NIPA-mismatched haploidentical hematopoietic stem cell transplantation for patients with hematological malignancies

The objective of this study was to compare clinical outcomes between noninherited maternal antigen (NIMA)-mismatched and noninherited paternal antigen (NIPA)-mismatched haploidentical hematopoietic stem cell transplantation (haplo-HSCT) among patients with hematological malignancies and perform a subgroup analysis. We retrospectively analyzed 378 patients with hematological malignancies who received haplo-HSCT from NIMA-mismatched (n = 201) and NIPA-mismatched (n = 177) donors between January 2012 and December 2017. The cumulative incidence of 100-d grades II-IV acute graft-versus-host disease (aGVHD) (19.2% vs. 32.8%, P = 0.003) was significantly lower in NIMA mismatch. Multivariate analysis showed that NIMA mismatch was associated with lower incidence of grades II-IV aGVHD and better overall survival (OS) and disease-free survival (DFS). According to the subgroup analysis, the clinical outcomes of older and/or female NIMA mismatches were comparable to those of younger and/or male NIPA mismatches with respect to grades II-IV aGVHD, chronic GVHD (cGVHD), nonrelapse mortality (NRM), relapse, DFS, and OS. In conclusion, this study confirmed the NIMA effect on aGVHD and demonstrated that NIMA mismatch was associated with better survival. In the NIMA mismatch context, donor age and sex did not seem to influence haplo-HSCT, which provides a basis for the selection of sibling donors.

Incognito: Are Microchimeric Fetal Stem Cells that Cross Placental Barrier Real Emissaries of Peace?

Chimerism occurs naturaly throughout gestation and can also occur as a consequence of transfusion and transplantation therapy. It consists of the acquisition and long-term persistence of a genetically distinct population of allogenic cells inside another organism. Previous reports have suggested that feto-maternal microchimerism could exert a beneficial effect on the treatment of hematological and solid tumors in patients treated by PBSCT. In this review we report the mechanism of transplacental fetal stem cell trafficking during pregnancy and the effect of their long-term persistence on autoimmunity, GVHD, PBSCT, cancer and stem cell treatment.

Naturally acquired microchimerism: implications for transplantation outcome and novel methodologies for detection

Microchimerism represents a condition where one individual harbors genetically distinct cell populations, and the chimeric population constitutes <1% of the total number of cells. The most common natural source of microchimerism is pregnancy. The reciprocal cell exchange between a mother and her child often leads to the stable engraftment of hematopoietic and non-hematopoietic stem cells in both parties. Interaction between cells from the mother and those from the child may result in maternal immune cells becoming sensitized to inherited paternal alloantigens of the child, which are not expressed by the mother herself. Vice versa, immune cells of the child may become sensitized toward the non-inherited maternal alloantigens of the mother. The extent of microchimerism, its anatomical location, and the sensitivity of the techniques used for detecting its presence collectively determine whether microchimerism can be detected in an individual. In this review, we focus on the clinical consequences of microchimerism in solid organ and hematopoietic stem cell transplantation, and propose concepts derived from data of epidemiologic studies. Next, we elaborate on the latest molecular methodology, including digital PCR, for determining in a reliable and sensitive way the extent of microchimerism. For the first time, tools have become available to isolate viable chimeric cells from a host background, so that the challenges of establishing the biologic mechanisms and function of these cells may finally be tackled.

Maternal-fetal cellular trafficking: clinical implications and consequences

PURPOSE OF REVIEW

Maternal-fetal cellular trafficking (MFCT) is the bidirectional passage of cells between mother and fetus during pregnancy. This results in the presence of fetal cells in the maternal circulation, known as fetal microchimerism, and maternal cells in the fetal circulation, known as maternal microchimerism. The biologic role of this transplacental cellular trafficking during pregnancy is not known, although it has been implicated in development of the fetal immune system, tolerance mechanisms during pregnancy, tissue repair in autoimmune disease and cancer, and immune surveillance.

RECENT FINDINGS

Clinical utility of MFCT has been identified in prenatal testing for aneuploidies and prediction of pregnancy complications. Additionally, this transplacental passage of cells has been implicated in the delicate balance between immunologic priming and tolerance, which can influence the occurrence of autoimmune disease and transplantation outcomes. Ongoing studies are evaluating the utility of microchimerism in predicting the risk of graft rejection in transplantation.

SUMMARY

In this review, we will discuss the clinical implications of MFCT in pregnancy, fetal surgery, autoimmune disease, transplantation, and cancer.