MHC II gene knockout in tissue engineering may prevent immune rejection of transplants

Simultaneous editing of TCR, HLA-I/II and HLA-E resulted in enhanced universal CAR-T resistance to allo-rejection

Introduction

The major challenge for universal chimeric antigen receptor T cell (UCAR-T) therapy is the inability to persist for a long time in patients leading to inferior efficacy clinically. The objective of this study was to design a novel UCAR-T cell that could avoid the occurrence of allo-rejection and provide effective resistance to allogeneic Natural Killer (NK) cell rejection, together with the validation of its safety and efficacy ex vivo and in vivo.

Methods

We prepared T-cell receptor (TCR), Human leukocyte antigen (HLA)-I/II triple-edited (TUCAR-T) cells and evaluated the anti-tumor efficacy ex vivo and in vivo. We measured the resistance of exogenous HLA-E expressing TUCAR-T (ETUCAR-T) to NK rejection by using an enhanced NK. Furthermore, we established the safety and efficacy of this regimen by treating Nalm6 tumor-bearing mice with a repeated high-dose infusion of ETUCAR-T. Moreover, we analyzed the effects of individual gene deficiency CAR-T on treated mice and the changes in the transcriptional profiles of different gene-edited T cells via RNA-Seq.

Results

Data showed that HLA-II editing didn't impair the anti-tumor efficacy of TUCAR-T ex vivo and in vivo and we found for the first time that HLA-II deficiency could facilitate the persistence of CAR-T. Contrastively, as the most commonly eliminated target in UCAR-T, TCR deficiency was found to be a key disadvantageous factor for the shorter-term anti-tumor efficacy in vivo. Our study demonstrated ETUCAR-T could effectively resist allogeneic NK rejection ex vivo and in vivo.

Discussion

Our research provided a potential and effective strategy for promoting the persistence of UCAR-T cells in clinical application. And it reveals the potential key factors of the poor persistence of UCAR-T along with new insights for future development.

Modulation of the secretion of mesenchymal stem cell immunoregulatory factors by hydrolyzed fish collagen

The aim of the present study was to investigate the possible immunomodulatory effects of osteogenically differentiated bone marrow mesenchymal stem cells induced by hydrolyzed fish collagen. Marine biomaterials have attracted significant attention for their environmental friendliness and renewability. Hydrolyzed fish collagen (HFC) has been discovered to induce the osteoblastic differentiation of stem cells, which underlies the foundation for its application in tissue engineering. Stem cells and their biomaterial carriers face acute immune rejection mediated by host macrophages. A potential strategy for combatting rejection in stem cell therapy is to modify the polarization of macrophages. However, whether HFC-induced mesenchymal stem cells maintain their immunomodulatory ability remains to be determined. To understand this phenomenon, a co-culture model of direct contact was established between bone marrow mesenchymal stem cells (BMSCs) and RAW264.7 macrophages, where the secretion of nitrous oxide from macrophages was measured using Griess colorimetric assay. ELISAs were performed to measure the secretion of interleukin (IL)-1β, IL-6, transforming growth factor (TGF)-β and IL-10, whilst reverse transcription-quantitative PCR was used to assess the expression levels of IL-1β, IL-6, CD206, resistin-like molecule α (FIZZ1) and prostaglandin E2 receptor 4 (EP4). In addition, the expression levels of relevant proteins in the phosphorylated-cyclic AMP-responsive element-binding protein-CCAAT/enhancer-binding protein β (EBPβ) pathway were investigated using western blotting. HFC-induced BMSCs were found to suppress the expression levels of IL-1β and IL-6, whilst increasing the expression levels of CD206 and FIZZ1 in RAW264.7 macrophages. HFC-induced BMSCs also inhibited the secretion of IL-1β and IL-6, whilst promoting the secretion of TGF-β and IL-10 secretion from RAW264.7 macrophages. Mechanistic studies using western blotting discovered that HFC stimulated the secretion of prostaglandin E2 from BMSCs, which subsequently increased the expression of EP4 on the macrophages. EP4 then increased the expression levels of C/EBPβ and arginase 1 further. In conclusion, results from the present study suggested that following induction with HFC, BMSCs maintain their immunomodulatory activity.

Mesenchymal stromal cells attenuate sevoflurane-induced apoptosis in human neuroglioma H4 cells

BACKGROUND

Inhalation of sevoflurane can induce neuronal apoptosis, cognitive impairment and abnormal behaviors. Bone marrow mesenchymal stem cells (MSCs) can secret neurotrophic factors and cytokines to protect from oxidative stress-related neuronal apoptosis. However, whether MSCs can protect from sevoflurane-induced neuronal apoptosis and the potential mechanisms are unclear.

METHODS

A non-contact co-culture of MSCs with human neuroglioma H4 cells (H4 cells) was built. H4 cells were co-cultured with MSCs or without MSCs (control) for 24 h. The co-cultured H4 cells were exposed to 4% sevoflurane for 6 h. The levels of caspase-3, reactive oxygen species (ROS), adenosine triphosphate (ATP), and the release of cytochrome C were determined by Western blot and fluorescence assay.

RESULTS

Sevoflurane exposure significantly elevated the levels of cleaved caspase 3 and Bax in H4 cells. However, these phenomena were significantly offset by the co-culture with MSCs in H4 cells. Co-culture with MSCs before, but not after, sevoflurane exposure, significantly attenuated sevoflurane-induced ROS production in H4 cells. MSCs prevented sevoflurane-mediated release of cytochrome C from the mitochondria and production of ATP in H4 cells.

CONCLUSIONS

Our study indicated that soluble factors secreted by MSCs attenuated the sevoflurane-induced oxidative stress and apoptosis of neuronal cells by preserving their mitochondrial function.

Porcine urinary bladder matrix-polypropylene mesh: a novel scaffold material reduces immunorejection in rat pelvic surgery

INTRODUCTION AND HYPOTHESIS

The present study set out to modify polypropylene vaginal surgical material using porcine urinary bladder matrix (UBM) in order to improve biocompatibility. The aim was to develop a compound scaffold that induced less vaginal erosion and to evaluate host immunoreactivity to this material in vivo.

METHODS

Forty-eight Sprague-Dawley rats were randomly divided into four equal groups. One group underwent a sham operation, and the other groups underwent vaginal implantation with different materials: UBM (U); UBM + polypropylene (UP); or polypropylene (P). The host tissue response was determined by macro-observation, and by histological and immunohistochemical methods at 7, 14, 21, or 28 days after surgery.

RESULTS

The inflammation reaction was strongest throughout the entire observation time in Group P, but was weaker and had a tendency to decrease with time in Groups U and UP. The presence of the UBM material in the compound scaffold allowed the polypropylene to fuse with newly proliferating surrounding tissue and resulted in less rejection of the material by the host, as indicated by the reduced appearance of CD4-, and CD8-positive cells.

CONCLUSIONS

Porcine UBM allowed mechanical isolation of polypropylene, and also reduced the immune reaction to polypropylene. This study suggests that the UBM + polypropylene compound scaffold may be a promising material for clinical use in pelvic reconstruction surgery.