Disparate hypervariable region-1 of mitochondrial DNA did not induce skin allograft rejection in cloned porcine models

Donor plasma mitochondrial DNA is associated with antibody-mediated rejection in renal allograft recipients

We previously showed that donor plasma mitochondrial DNA (dmtDNA) levels were correlated with renal allograft function. The aim of the current study was to determine whether dmtDNA levels are associated with the occurrence of antibody-mediated rejection (ABMR). This is a retrospective open cohort study comprised of 167 donors and 323 recipients enrolled from January 2015 to December 2017. We quantified the mtDNA level present in donor plasma using quantitative real-time polymerase chain reaction. The average plasma dmtDNA level in the acute rejection (AR) group was higher than that of the control group (0.156 versus 0.075, p<0.001). Multivariate logistic regression analysis showed that dmtDNA levels were also significantly associated with AR (OR=1.588, 95% CI 1.337-4.561, p<0.001). When the dmtDNA level was >0.156, the probability of AR was 62.9%. The plasma dmtDNA level in the ABMR group was significantly higher than that of the T cell-mediated rejection group (0.185 versus 0.099, p=0.032). The area under the receiver operating characteristic curve of dmtDNA for prediction of ABMR was as high as 0.910 (95% CI 0.843-0.977). We demonstrated that plasma dmtDNA was an independent risk factor for ABMR, which is valuable in organ evaluation. dmtDNA level is a possible first predictive marker for ABMR.

Teratoma: from spontaneous tumors to the pluripotency/malignancy assay

A teratoma is a benign tumor containing a mixture of differentiated tissues and organotypic derivatives of the three germ layers, while a teratocarcinoma also contains embryonal carcinoma cells (EC cells). Experimental teratomas and teratocarcinomas have been derived from early mammalian embryos transplanted into the adult animal (ectopic sites). In the rat, the pluripotency of the transplanted epiblast was demonstrated and a quantifiable restriction of developmental potential persisted after subsequent transplantation of chemically defined cultivated postimplantation embryos. The rat is nonpermissive for teratocarcinoma development and rat pluripotent cell lines have been established only recently. Transplantation of mouse embryos, epiblast, or embryonic stem cells (mESCs) gave rise to teratocarcinomas. The pluripotency of reprogrammed human cells has been tested by a 'gold standard' trilaminar teratoma assay in immunocompromised mice in vivo. Human pluripotent stem cells proposed for use in regenerative medicine such as human embryonic stem cell (hESC), human nuclear-transfer/therapeutic cloning embryonic stem cell (NT-ESC), or human induced pluripotent stem cell (hiPSC) lines, once differentiated in vitro to the desired cell type, should be again tested in a long-term animal teratoma assay to exclude their malignancy. Such an approach led to a recently implemented human therapy with retinal pigmented epithelium. For greater biosafety, the teratoma assay should be standardized and complemented by assessments of mutations/epimutations, RNA/protein expression, and possible immunogenicity of autologous pluripotent cells. Furthermore, the standardized teratoma assay should be directed more to the assessment of EC/malignant cell features than of differentiated tissues, especially after a unique case of human therapy with neural stem cells was found to lead to malignancy. For further resources related to this article, please visit the WIREs website.