Donor MHC gene to mitigate rejection of transplantation in recipient mice / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Donor organ rejection continues to be a significant problem for patients receiving transplants. We therefore tested whether transferring a donor's major histocompatibility complex (MHC) gene to the recipient would mitigate the rejection of transplanted hearts in mice.</p><p><b>METHODS</b>H-2K(k) gene from donor mice was amplified using nested polymerase chain reaction (PCR) and ligated into a mammalian expression vector, which was then transfected into thymus ground mass cells collected from the recipients. Clones stably expressing the transgene were then injected into the recipients' thymus visualized using ultrasound. Control mice were administered cells previously transfected with empty vector. Following heart transplantation, cardiac activity was monitored electrocardiographically. Recipient thymus cells were tested for MHC antigenicity using flow cytometry and spleen cells were subjected to mixed lymphocyte culture tests. Finally, the transplanted hearts were sectioned, stained and examined under light microscopy.</p><p><b>RESULTS</b>Southern analysis following nested PCR revealed clear expression of H-2K(k) gene. Following transplantation, electrocardiosignals were detectable highly significantly longer in recipients administered thymal cells expressing donor H-2K(k) than in those receiving control cells. Flow cytometric analysis using an anti-H-2K(k) antibody confirmed its expression in H-2K(k) treated recipients but not in control mice. Mixed lymphocyte cultures containing H-2K(k) treated cells showed significantly less proliferation than those containing control cells. Hearts from control mice showed substantially greater lymphocyte infiltration than those from H-2K(k) treated mice and large areas of necrosis.</p><p><b>CONCLUSION</b>Rejection of transplanted hearts can be mitigated substantially by introducing the donor's MHC into the recipient.</p>

High-level expression of phenylalanine ammonia-lyase in Lactococcus Lactis via synthesized sequence based on bias codons / 生物工程学报

To construct a safer and more efficient gene engineering Lactococcus Lactis for expressing phenylalaine ammonia lyase (PAL) which will be benefit for PKU therapy, pal cDNA of Parsly and synthesized sequence based on Lactococcus Lactis bias codons were recombined into two Lactococcus Lactis NICE systems. The activities of the expressed PAL were detected, and the effect of Lactococcus Lactis bias codons on the expression of exterior protein was analyzed. The results showed that the expression level of PAL was increased by using Lactococcus Lactis bias codons in both Lactococcus Lactis NICE systems. Through which several safer andmore efficient strains of the gene engineering Lactococcus Lactis were obtained.