iPSC-Derived Platelets Depleted of HLA Class I Are Inert to Anti-HLA Class I and Natural Killer Cell Immunity

Abstract

The ex vivo production of platelets depleted of human leukocyte antigen class I (HLA-I) could serve as a universal measure to overcome platelet transfusion refractoriness caused by HLA-I incompatibility. Here, we developed human induced pluripotent cell-derived HLA-Ideficient platelets (HLA-KO iPLATs) in a clinically applicable imMKCL system by genetic manipulation and assessed their immunogenic properties including natural killer (NK) cells, which reject HLA-I downregulated cells. HLA-KO iPLATs were deficient for all HLA-I but did not elicit a cytotoxic response by NK cells in vitro and showed circulation equal to wild-type iPLATs upon transfusion in our newly established Hu-NK-MSTRG mice reconstituted with human NK cells. Additionally, HLA-KO iPLATs successfully circulated in an alloimmune platelet transfusion refractoriness model of Hu-NK-MISTRG mice. Mechanistically, the lack of NK cell-activating ligands on platelets may be responsible for evading the NK cell response. This study revealed the unique non-immunogenic property of platelets and provides a proof of concept for the clinical application of HLA-KO iPLATs.

Generation and manipulation of human iPSC-derived platelets

“…Other proposals include overexpressing HLA-E [ 152 ] or retaining the expression of HLA-C [ 153 ]. Interestingly, we found that B2M-KO iPSC-PLTs, which are completely devoid of HLA-I expression, do not elicit an NK cell response in vitro [ 147 ]. To confirm the circulation in vivo in the presence of NK cells, we developed humanized immune system (HIS) mice, which were reconstituted with a sufficient number of human NK cells to reject B2M-knockout iPSC-derived hematopoietic cells.…”

“…To confirm the circulation in vivo in the presence of NK cells, we developed humanized immune system (HIS) mice, which were reconstituted with a sufficient number of human NK cells to reject B2M-knockout iPSC-derived hematopoietic cells. B2M-KO iPSC-PLTs circulated comparably with wild-type iPSC-PLTs in the NK cell reconstituted HIS mice and also circulated in the presence of anti-HLA-I antibody [ 147 ]. While this observation removes the concern of NK cells rejecting HLA-KO platelets, the reason for the low immunogenicity of platelets remains unknown.…”

Development of platelet replacement therapy using human induced pluripotent stem cells

“…It is estimated that the 10 most frequent lines of iPSCs with homozygous HLA could cover approximately 50% of the Japanese population. Ultimately, owing to the capability of gene editing iPS cells, HLA‐I nullified iPS cell‐derived platelets have also been developed (Feng et al., 2014; Gras et al., 2013; Suzuki et al., 2020) These cells can serve as a universal product and do not require a library of different HLA haplotypes. Furthermore, they are suitable as a platform for further modified products, which may lead to novel therapies using platelets.…”

iPSC-Derived Liver Organoids: A Journey from Drug Screening, to Disease Modeling, Arriving to Regenerative Medicine

“…After differentiation into endothelial-like and cardiomyocyte-like cells, immunogenicity tests revealed no cytokines or antibody response when transplanted into allogenic humanized mice [ 25 ]. Similar approaches have been achieved for the generation of iPSC-derived HLA-universal platelets lacking HLA class I expression by knocking-out β2-Microglobulin gene [ 26 , 27 ]. Taken together, iPSCs can be considered an attractive tool for developing regenerative medicine applications.…”