Beijing Rose Genomics Corp.Ltd

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Back Ground

Xenotransplantation is one of the effective options for treating end-stage organ failure and addressing organ shortages. The donors selected for early xenotransplantation research were mainly non-human primates, which are no longer suitable as donor organs due to factors such as moral ethics and long reproductive cycles. Pigs are similar in organ size, physiological and biochemical indicators to humans, and have advantages such as short reproductive cycle, high number of offspring, and low cost, making them the best choice for xenograft donors. However, the strong immune rejection reaction between different species seriously hinders its application, among which porcine leukocyte antigen is one of the genetic factors causing acute cellular rejection. Therefore, ensuring high similarity between donor pig SLA and recipient human HLA directly determines the success rate of xenotransplantation.

Scientific Research

Medical research

Xenograft organ transplantation

Product Service Introduction

1. Identification and lymphatic toxicity experiments (genetic testing services) of SLA in pigs

Based on NGS (Next Generation Sequencing Technology Platform), the antigen genotype of porcine leukocyte antigen SLA was determined by deep sequencing and comparison with gene data in the database. Combined with lymphotoxicity experiments, the degree of rejection between pig organs and patient HLA was further determined.

2. Provide customized breeding and optimization plans of donor pigs, mainly including:

(1) Pig breed selection and health assessment; (2) Sequencing, sequence alignment, and annotation of collected samples; (3) Lymphotoxic cell assay to evaluate organ compatibility; (4) Posttransplant monitoring; In addition, in response to the need for gene editing of pig embryos, we will also provide services such as gene editing, microinjection, embryo transfer, and adult animal delivery.

Scheme Flowchart

Free DNA from donor, abbreviated as dd-cfDNA, refers to free DNA fragments from donor organs present in the recipient's blood and urine. These fragments carry information about the donor organ and can be used to evaluate the health status and damage site of the donor organ.

dd-cfDNA Introduction

The Detection Technology dd-cfDNA

Organ transplantation is an effective treatment for advanced organ diseases, but successful organ transplantation and achieving a longer survival time require going through many "levels", including immune tolerance and rejection hurdles, infection hurdles, and adaptation to new organs. Rejection and infection are common complications that affect the quality of life and safety of transplant patients after surgery. Research from multiple international transplant centers has found that dd cfDNA technology can detect graft rejection and replace traditional puncture biopsy. It has even become a routine detection method in foreign countries.

If the donor organ experiences rejection after transplantation, the dd cfDNA content in blood and urine will increase. Based on the different levels, the severity of rejection can be evaluated. The content of free DNA in blood and urine varies depending on the type of rejection reaction, which can indicate different parts of the rejection reaction. This technology is very sensitive, and research has found that the concentration of free DNA has started to rise two months before the occurrence of rejection, which can detect early rejection reactions.

The Role Of dd-cfDNA In Transplantation

The dd-cfDNA detection provided by our company uses a second-generation gene sequencing platform to detect the content of donor derived free DNA in blood or urine, which can predict the damage status of the graft and serve as a diagnostic indicator for rejection reactions. It has the advantages of non-invasive, high sensitivity, and real-time monitoring, so it is also known as liquid biopsy. We extract free DNA from blood or urine, analyze low-frequency mutations with mutation frequencies less than 0.2 in SNP, and use maximum likelihood estimation to statistically analyze all mutation frequencies ≤ 0.2 to obtain dd cfDNA concentration values, which can detect early rejection reactions.

STR Introduction

STR-PCR Detection

Short tandem repeats (STRs) have a high degree of polymorphism and genetic stability. As genetic DNA molecular markers, they have been widely used in many fields such as genetic mapping, linkage analysis, parent-child identification, disease gene mapping, and species polymorphism research.

The STR-PCR monitoring method has been used to monitor the status before and after allogeneic hematopoietic stem cell transplantation. Collect blood samples from pre transplant, post transplant recipients, and donors for STR site analysis, and compare the analysis results to visually, reliably, and clearly observe the chimeric state of the patient after transplantation. The formation of chimeras is a dynamic process, and complete donor source states and mixed chimeras can appear at different stages after transplantation, and can transform with the evolution of the disease and time. Therefore, continuous monitoring of chimeras using STR-PCR technology can early identify graft implantation, detect residual small lesions, predict transplant effects, and guide clinical timely adoption of corresponding treatment measures.

The genetic research data of STR population using detection technology shows that there are 15 STR loci (CSF1PO, D13S317, D16S539, D18S51, D19S433, D21S11, D2S1338, D3S1358, D5S818, D7S820, D8S1179, FGA, THO1, TPOX, and vWA) with high genetic polymorphism in the Han population, which are suitable for individual identification, parent-child identification, and basic data for establishing STR gene databases in the Han population. Therefore, these 15 STR gene loci can effectively monitor the transplant status of patients before and after transplantation.

Collect peripheral blood or bone marrow from donors and recipients before surgery, and collect peripheral blood or bone marrow every month or according to schedule after surgery. After DNA extraction, use specific primers labeled with fluorescence to multiplex amplify the above STR sites. After capillary electrophoresis and fragment analysis, calculate the chimerism rate. Hematopoietic chimerism is generally divided into three types. When the percentage of donor cells occupying the recipient's bone marrow or peripheral blood exceeds 95%, that is, the donor cells are completely implanted, which is called complete chimerism. If the recipient cells still appear in the bone marrow or peripheral blood after transplantation, both donor and recipient cell components can be detected simultaneously, with donor cells accounting for 5-95%, which is called mixed chimerism. Microchimerism refers to donor cells<5%.

STR-PCR In Hematopoietic Stem Cell Transplantation Application

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