Stem Cell Donor Research Articles

The Novel HLA‐DPB1*1327:01 Allele Identified by Next‐Generation Sequencing in a Potential Haematopoietic Stem Cell Donor

ABSTRACTThe novel allele HLA‐DPB1*1327:01 has a non‐synonymous mutation difference compared with HLA‐DPB1*04:01:01.

Cell therapy for end-stage liver disease: Current state and clinical challenge.

Liver disease involves a complex interplay of pathological processes, including inflammation, hepatocyte necrosis, and fibrosis. End-stage liver disease (ESLD), such as liver failure and decompensated cirrhosis, has a high mortality rate, and liver transplantation is the only effective treatment. However, to overcome problems such as the shortage of donor livers and complications related to immunosuppression, there is an urgent need for new treatment strategies that need to be developed for patients with ESLD. For instance, hepatocytes derived from donor livers or stem cells can be engrafted and multiplied in the liver, substituting the host hepatocytes and rebuilding the liver parenchyma. Stem cell therapy, especially mesenchymal stem cell therapy, has been widely proved to restore liver function and alleviate liver injury in patients with severe liver disease, which has contributed to the clinical application of cell therapy. In this review, we discussed the types of cells used to treat ESLD and their therapeutic mechanisms. We also summarized the progress of clinical trials around the world and provided a perspective on cell therapy.

Successful colonization of the testicular germinal epithelium by bone marrow stem cells producing spermatozoa of donor genotype is rare

AbstractBackgroundIt is not known whether bone marrow stem cells when injected intravenously for a bone marrow transplant colonize the human testicular epithelium. No previous studies of sperm genotype after bone marrow transplantation are reported.ObjectivesTo differentiate host from donor genotype in spermatozoa of men who have undergone successful bone marrow transplants.Materials and methodsTriplet DNA samples (spermatozoa, blood, and hair) obtained from men who had recovered sperm production after bone marrow transplant were genotyped using 44 autosomal and three sex‐related single nucleotide polymorphisms to determine the tissue genotype in pairwise comparisons of DNA profiles.ResultsParticipants were 14 men at a median of 5.5 years after allogeneic bone marrow transplant who had a median sperm output of 77 million spermatozoa/ejaculate. In 14/14 the donor (leukocyte) DNA genotype differed significantly from the spermatozoa and hair genotypes whereas hair and sperm genotypes showed no variations.DiscussionThese data suggest that paternity after a successful bone marrow transplant is likely to be of the host and not the donor's genetic origins. The study's small sample size reflects the paucity of eligible man with recovered spermatogenesis after bone marrow transplant and represents preliminary evidence. A large‐scale epidemiological analysis to estimate the frequency of bone marrow donor stem cell colonization of the testicular germinal epithelium based on progeny sex ratio and frequency of female donors is proposed.ConclusionSuccessful colonization of the testicular germinal and hair follicle epithelia by allogeneic bone marrow transplant donor stem cells is rare or does not occur.

No Conflicting Loyalties in Parents When Their Healthy Child Donates Stem Cells to a Severely Ill Sibling: An Interview Study.

Background: When a potential stem cell donor to a seriously ill child is a healthy sibling below 18 years, Swedish parents have the legal right and obligation to decide on behalf of the donor child. However, there are potentially conflicting loyalties when parents have one severely ill child in need for a cure and one healthy child who will be subjected to medical procedures. This study explored parents' experiences related to their decision on stem cell donation, as well as ethical considerations in the donation process where outcomes are uncertain. Method: Individual interviews were performed with 18 parents of 13 minor donors after successful hematopoietic stem cell transplantations. Interviews were analyzed using inductive Reflexive Thematic Analysis. Results: The parents were living with the threat of losing a child, and in this context, the main theme No conflicting loyalties was found and included four subthemes; Focus on the ill child, Sibling as the preferred donor, Obvious that the healthy child should donate, and Keep on keeping on. Conclusion: When a healthy child is a potential donor to an ill sibling, their parents' main focus is on the cure for the ill child. The lack of obvious conflicting loyalties among parents highlights the need to secure an ethical process for healthy minor donors and the importance of a separate donor advocate for these minor donors.

Harnessing Global HLA Data for Enhanced Patient Matching in iPSC Haplobanks

Several countries have either developed or are developing national induced pluripotent stem cell (iPSC) banks of cell lines derived from donors with HLA homozygous genotypes (two identical haplotypes) prevalent in their local populations to provide immune matched tissues and cells to support regenerative medicine therapies. This ‘haplobank’ approach relies on knowledge of the HLA genotypes of the population to identify the most beneficial haplotypes for patient coverage, and ultimately identify donors or cord blood units carrying two copies of the target haplotype. A potentially more efficient alternative to a national bank approach is to assess the haplotypes required to provide global patient coverage and to produce a single, global haplobank. Toward that end, we have developed an algorithm to prioritize HLA haplotypes that optimize coverage across the global population.We analyzed data from eighteen countries participating in the Global Alliance for iPS Therapy (GAiT). A representative pool of HLA genotypes, reflecting the HLA of patients, was derived by sampling from each country's WMDA hematopoietic stem cell donor registry, or surrogate population. An algorithm was created based on HLA-A, -B and -DRB1 haplotype homozygous types with population HLA matching coverage defined by the absence of Host versus Graft (HvG) mismatches at these loci. HLA matching coverage was determined by iteratively selecting HLA haplotypes that provide the largest coverage against patient HLA genotypes sampled from the same population, excluding genotypes compatible with previous iterations. The top 10 haplotypes for each of the 18 countries were identified with patient coverage ranging from 19.5% in Brazil to 63.8% in Japan, with a mean coverage of 33.3%. In a ‘global’ model, utilizing the 180 most frequent haplotypes across all 18 populations (equivalent to 10 lines per country), the patient coverage ranged from 54.6% in India to 81.7% in Sweden, with a mean of 68.4%. Our findings demonstrate that global collaboration could more than double the potential for patient HLA matching coverage.Interrogation of unrelated hematopoietic stem cell donor registry and cord blood bank HLA data demonstrated that HLA-A, -B, and -DRB1 homozygous donors for the top 180 global haplotypes are widely available. These results show that a globally coordinated strategy for haplobanking would reduce redundancy and allow more patients to be treated with the same investment.

Generation of human induced pluripotent stem cell (DMSCi001-A) line from hematopoietic stem cells of a healthy female donor

Hematopoietic stem cell isolated from a healthy 39-year-old woman were successfully reprogrammed and transformed into induced pluripotent stem cell (iPSCs) by using the integration-free episomal vector included OCT3/4/shp53, Sox2/KLF4, L-MYC/LIN28 and EBNA-1 reprogramming factors. The transformed iPSC lines were cultured and expanded under feeder-free condition. They demonstrated the normal karyotype, expressed pluripotency markers and differentiated into cells derived from the three germ layers. These iPSCs are capable of differentiating into numerous cell subtypes for the purposes of drug discovery and mechanism investigation.

Factors influencing unrelated stem cell donation a mixed-methods integrated systematic review.

There is an imbalance between demand for and availability of stem cell donors worldwide. The purpose of this systematic review is to provide the first comprehensive understanding of facilitators and barriers influencing unrelated stem cell donation (USCD) in adults, through a data synthesis of qualitative and quantitative evidence. Identification of the facilitators and barriers associated with stem cell donation intention and behaviour is essential to inform the development of behaviour change interventions to meet the current demand. Four databases were searched (Embase, PsycINFO, MEDLINE and CINAHL) and the last search was in February 2021. The search was limited to studies written in English and published from 1980 to present. Screening, quality assessment, data extraction and data synthesis incorporating the COM-B model were undertaken in line with the Joanna Briggs Institute methodology for an integrated mixed-methods review. Fifty studies were included in the review, analysis and mapping produced four integrated findings. Donation-related knowledge was a facilitator and conversely, lack of knowledge was a barrier to donation related behaviours. Perceived convenience, positive social influences, religious beliefs and the accessibility of positive donation-related social norms promoted positive donation related behaviours. Altruism and sense of duty were the most commonly cited motives for donation related behaviours.Through mapping to the COM-B model, Communication/Marketing, and Service Provision are the primary policy categories that can be used to change donation related behaviours. Future interventions should focus on targeted education regarding unrelated stem cell donation and creating recruitment campaigns that emphasise the life-saving potential of donation.

Characterization of clonal dynamics using duplex sequencing in donor-recipient pairs decades after hematopoietic cell transplantation.

After allogeneic hematopoietic cell transplantation (HCT), a very small number of donor stem cells reconstitute the recipient hematopoietic system, whereas the donor is left with a near-normal pool of stem cells. We hypothesized that the increased replicative stress on transplanted donor cells in the recipient could lead to the disproportionate proliferation of clonal hematopoiesis (CH) variants. We obtained blood samples from 16 related donor-recipient pairs at a median of 33.8 years (range: 6.6 to 45.7) after HCT, including the longest surviving HCT recipients in the world. For 11 of 16 pairs, a donor sample from the time of HCT was available for comparison. We performed ultrasensitive duplex sequencing of genes recurrently mutated in myeloid malignancies and CH, as well as a set of functionally neutral genomic regions representative of human genomic content at large. CH variants were observed in all donors, even those as young as 12 years old. Where donor pre-HCT sample was available, the average mutation rate in donors compared to recipients post-HCT was similar (2.0% versus 2.6% per year, respectively) within genes recurrently mutated in myeloid malignancies. Twenty-two (5.6%) of the 393 variants shared between paired donors and recipients post-HCT showed ≥10-fold higher variant allele frequency (VAF) in the recipient. A longer time since HCT was positively associated with the expansion of shared variant VAFs in the recipient. In conclusion, even decades after HCT, there does not appear to be widespread accelerated clonal expansion in the transplanted cells, highlighting the immense regenerative capacity of the human hematopoietic system.

Perception of Matched Sibling Hematopoietic Stem Cell Donor about Donation of Stem Cells

Allogeneic hematopoietic stem cell transplantation (HSCT) is the curative treatment option for a variety of hematological disorders. Usually, stem cells for HSCT are obtained from matched related donors through bone marrow harvest or apheresis. Although stem cell donation is relatively a safe procedure, there are many psychosocial concerns among potential donors regarding the donation of stem cells and its possible complications. The present study aims to understand the experience of being a hematopoietic stem cell donor for a sick sibling. Eighty hematopoietic stem cell sibling donors were interviewed with a self-structured questionnaire comprising of 3 domains-intrinsic and extrinsic motivators and deterrents. Data were analyzed using descriptive and inferential statistics using IBM SPSS® Statistics version 20.0. The present study found that nearly half of them (47.5%) were <30 years of age with 52.5% being male, 57.5% were married and 53.8% were employed. 43.8% were graduates of which 7.5% had a family income of <Rs.5,000. 51.2% hailed from rural backgrounds. The majority of them (90%) of them had no co-morbidities. All of them underwent local anesthesia and had peripheral stem cells as the source of harvest. None of them had a previous history of stem cell donation. The majority of the matched sibling donors were primarily influenced by intrinsic factors (median score-3.2). The influence of the deterrents is lesser than the influence of the motivators (median score-1). There is a statistically significant association between gender and the influence of extrinsic motivators (P = 0.024), marital status and deterrents (P = 0.003), and age and deterrents (P = 0.019) in the hematopoietic stem cell donation process. Among the deterring facets, the emotional concern of being responsible for the outcome of the transplant was the major barrier (45%). The family concern of taking up the burden of being a donor and a family member is the least deterring facet (62.5%). Among the intrinsic motivating facets, positive feelings (87.5%) and family loyalty (81.3%) were the major motivating factors whereas reinvesting back into the community was the least intrinsically motivating factor (32.5%). Among the extrinsic motivating facets, complete awareness of the donation process through explanation was the highly motivating factor (93.8%). Family pressure/social obligation was the least extrinsically motivating facet (83.8%). The study highlights the role of intrinsic motivation in the stem cell donation process and warrants for further exploration.

Nose-to-brain delivery of stem cells in stroke: the role of extracellular vesicles.

Stem cell transplantation offers a promising therapy that can be administered days, weeks, or months after a stroke. We recognize 2 major mitigating factors that remain unresolved in cell therapy for stroke, notably: (1) well-defined donor stem cells and (2) mechanism of action. To this end, we advance the use of ProtheraCytes, a population of non-adherent CD34+ cells derived from human peripheral blood and umbilical cord blood, which have been processed under good manufacturing practice, with testing completed in a phase 2 clinical trial in post-acute myocardial infarction (NCT02669810). We also reveal a novel mechanism whereby ProtheraCytes secrete growth factors and extracellular vesicles (EVs) that are associated with angiogenesis and vasculogenesis. Our recent data revealed that intranasal transplantation of ProtheraCytes at 3 days after experimentally induced stroke in adult rats reduced stroke-induced behavioral deficits and histological damage up to 28 days post-stroke. Moreover, we detected upregulation of human CD63+ EVs in the ischemic brains of stroke animals that were transplanted with ProtheraCytes, which correlated with increased levels of DCX-labeled neurogenesis and VEGFR1-associated angiogenesis and vasculogenesis, as well as reduced Iba1-marked inflammation. Altogether, these findings overcome key laboratory-to-clinic translational hurdles, namely the identification of well-characterized, clinical grade ProtheraCytes and the elucidation of a potential CD63+ EV-mediated regenerative mechanism of action. We envision that additional translational studies will guide the development of clinical trials for intranasal ProtheraCytes allografts in stroke patients, with CD63 serving as a critical biomarker.

Evaluation of Female Recipient Infertility and Donor Spermatogonial Purification for Germ Cell Transplantation in Paralichthys olivaceus.

Since the advent of germ cell transplantation (GCT), it has been widely used in shortening the fish breeding cycle, sex-controlled breeding and the protection of rare and endangered fish. In this study, the effectiveness of female sterile recipient preparation and donor stem cell isolation and purification were comprehensively evaluated for spermatogonial stem cell transplantation (SSCT) in Paralichthys olivaceus. The best way to prepare sterile recipients was found to be giving three-year-old fish four intraovarian injections of busulfan (20 mg/kg body weight) combined with exposure to a high temperature (28 °C) after the spawning season compared with the two other ways, which induced apoptosis of most of the endogenous germ cells, resulting in shrinkage of the spawning plate and enlargement of the ovarian lumen. Further analysis showed that both the gonadosomatic index and germ-cell-specific vasa expression were significantly lower than those of the natural-temperature group before treatment (p < 0.05). A high percentage (>60.00%) of spermatogonial stem cells (SSCs) were obtained after isolation and purification and were transplanted into the prepared recipients. After three weeks of SSCT, the numbers of PKH26-labeled SSCs were increased in the ovaries of the recipients. These findings provide a basis for the establishment of an ideal SSCT technique using P. olivaceus females as the recipients, ultimately contributing to the efficient conservation of male germplasm resources and effective breeding.

N-803, an IL-15 Superagonist Complex as Maintenance Therapy After Allogeneic Donor Stem Cell Transplant for Acute Myeloid Leukemia or Myelodysplastic Syndrome; A Phase 2 Trial

Maintenance therapy may improve natural killer (NK) cell surveillance after allogeneic donor hematopoietic cell transplant (HCT) for myeloid malignancies and represents a potential approach to improve cure rates. Interleukin-15 (IL-15) enhances lymphocyte proliferation and antitumor activity. In a prior Phase 1 study of an IL-15 superagonist (N-803) in patients with AML who relapsed after HCT, we observed in vivo expansion of NK cells and antitumor responses. The primary objective of this Phase 2 trial was to determine if post-transplant N-803 could reduce relapse. We administered N-803 (n = 20) (dosed 6 mcg/kg subcutaneously [SQ] at day 60 after HCT to patients with myelodysplastic syndrome [MDS] or acute myeloid leukemia [AML] who were in complete remission [CR]). N-803 treatment was planned weekly, biweekly or every 4 weeks in 2 sequential cohorts. The most common adverse events after administration were self-limited injection sites skin rashes (n = 20). One week after an N-803 dose, we observed enhanced NK cell proliferation and improved antitumor cytotoxicity without inducing immune exhaustion. Five patients who developed acute graft versus host disease (aGVHD) after N-803 responded promptly to steroids and 4 patients developed chronic GVHD. Patients receiving >4 doses of N-803 had a 3-fold decrease in relapse at two years (P = .06). These findings support the safety, immune activation, and potential efficacy of N-803 to prevent relapse of AML/MDS after HSCT.

HLA Diversity in Transylvanian Ethnic Groups: Consequences for Hematopoietic Cell Transplantation

The HLA profile is essential in cell and tissue transplantation, particularly in patients with autoimmune conditions and infections. Due to the extreme polymorphism in certain HLA loci, it also serves as a key tool for population genetic analysis. This study aimed to identify the allele and haplotype distributions of HLA class I (A, B, and C) and class II (DRB1) genotypes in unrelated hematopoietic stem cell donors. A retrospective analysis was conducted between 2016 and 2020 on 9832 Transylvanian volunteers, divided into Romanian and Hungarian groups based on self-reported ethnicity. Using PCR-SSO for HLA typing, significant differences were found in allele frequencies between ethnic groups. A total of 19 HLA-A, 31 HLA-B, 14 HLA-C, and 13 HLA-DRB1 distinct allele groups were identified between ethnic groups. Notably, B*18, B*51, and C*12 were more frequent in Romanians, while B*44, B*40, and C*07 were more common in Hungarians. Differences in haplotype distributions were also observed, with HLA-A*02~B*18~C*07~DRB1*11 being significantly more frequent in Romanians. Understanding these population-specific HLA profiles can improve donor matching for hematologic diseases, enhancing patient outcomes and access to life-saving hematopoietic stem cell transplantation.

Posttransplant cyclophosphamide versus anti-thymocyte globulin versus combination for graft-versus-host disease prevention in haploidentical transplantation for adult acute myeloid leukemia: A report from the European Society for Blood and Marrow Transplantation Acute Leukemia Working Party.

The optimal choice for graft-versus-host disease (GVHD) prophylaxis in haploidentical stem cell transplantation (haplo-SCT) remains debatable. Posttransplant cyclophosphamide (PTCy) and anti-thymocyte globulin (ATG) are two common strategies, but little is known about their combination. Using the European Society for Blood and Marrow Transplantation (EBMT) registry, the authors identified 3649 adult patients with acute myeloid leukemia (AML) who underwent haplo-SCT in complete remission between 2007 and 2021 at 260 EBMT-participating centers who received either PTCy (n=2999), ATG (n=358), or combination prophylaxis (n=292). Cord blood transplants, combined bone marrow and peripheral grafts, and transplants with ex vivo graft manipulation were excluded. Median follow-up was 31.8 months. On multivariate analysis, adjusting for patient age and performance status, disease status at transplant, cytogenetic risk, conditioning intensity, stem cell source, female-to-male graft, and donor and patient CMV status, we present the following. Compared to PTCy, ATG had a higher risk of nonrelapse mortality (hazard ratio [HR], 1.6; p=.003), worse leukemia-free survival (HR, 1.4; p=.002), overall survival (HR,1.49; p=.0009), and GVHD-free and relapse-free survival (HR,1.29; p=.012). The combination of PTCy and ATG, however, led to significantly reduced rates of grade 2-4 (HR, 0.51; p=.0003) and grade 3-4 (HR, 0.5; p=.018) acute GVHD and did not affect any transplant outcomes compared to PTCy without ATG. The authors conclude that ATG alone is a less effective prophylaxis strategy compared to PTCy, however, the combination of PTCy and ATG is superior to either monotherapy. They propose that this combination could be considered a potential new standard of care for GVHD prophylaxis in haplo-SCT for AML.

Inflammatory Intracellular Signaling in Neurons Is Influenced by Glial Soluble Factors in iPSC-Based Cell Model of PARK2-Associated Parkinson's Disease.

Neuroinflammation is considered to be one of the driving factors in Parkinson's disease (PD). This study was conducted using neuronal and glial cell cultures differentiated from induced pluripotent stem cells (iPSC) of healthy donors (HD) and PD patients with different PARK2 mutations (PD). Based on the results of RNA sequencing, qPCR and ELISA, we revealed transcriptional and post-transcriptional changes in HD and PD neurons cultivated in HD and PD glial-conditioned medium. We demonstrated that if one or both of the components of the system, neurons or glia, is Parkin-deficient, the interaction resulted in the down-regulation of a number of key genes related to inflammatory intracellular pathways and negative regulation of apoptosis in neurons, which might be neuroprotective. In PD neurons, the stress-induced up-regulation of APLNR was significantly stronger compared to HD neurons and was diminished by glial soluble factors, both HD and PD. PD neurons in PD glial conditioned medium increased APLN expression and also up-regulated apelin synthesis and release into intracellular fluid, which represented another compensatory action. Overall, the reported results indicate that neuronal self-defense mechanisms contribute to cell survival, which might be characteristic of PD patients with Parkin-deficiency.

Benefits of serum protein electrophoresis as part of hematopoietic stem cell donor clearance

Benefits of serum protein electrophoresis as part of hematopoietic stem cell donor clearance

Seven-years post allogeneic hematopoietic stem cell transplantation pure red cell aplastic anemia cured with daratumumab: A case report and review of literature

BACKGROUND Allogeneic hematopoietic stem cell transplantation (Allo-HSCT) is currently the only viable method of curing patients with acute myeloid leukaemia. In 30% to 50% of patients, donors and recipients have some level of ABO blood group incompatibility. ABO blood group incompatibility can cause antibodies against the donor's red blood cells to persist in the recipient's body, resulting in a delay of several months in the recovery of red blood cells. A number of different treatments have been reported for post-transplant pure red cell aplastic anaemia (PRCA), such as plasmapheresis, donor lymphocyte infusions, anti-thymocyte globulin, rituximab and steroids. CASE SUMMARY A 41-year-old female diagnosed with acute myeloid leukaemia underwent peripheral blood allogeneic haematopoietic stem cell transplantation in November 2013 from an HLA matched unrelated donor. The donor was AB-positive and the recipient was O-positive. The patient was diagnosed with PRCA three months after receiving the donor stem cell transplant. After failing multiple lines of therapy, the patient applied for daratumumab. After receiving three doses of daratumumab, the patient developed a reticulocyte response and no longer required blood transfusions. CONCLUSION The use of daratumumab anti-CD38 for the remove of plasma cells is safe and effective and may be tried for refractory patients with PRCA after undergoing allo-HSCT for ABO incompatibility.

Prediction of CD34+ hematopoietic stem cells in healthy allogeneic stem cell donors on the Optia cell separator based on CE2: Which formula is more correlated with actual CD34+?

Peripheral blood-derived hematopoietic stem cells (HSCs) are widely used for various adult stem cell transplants. To obtain sufficient HSCs from healthy volunteer donors during the apheresis process and ensure that the donors are exposed to fewer apheresis-related side effects, calculation methods have been developed for the prediction of processed blood volume or CD34+ count. However, there is no consensus on a formula to predict the volume of blood to be processed or the number of stem cells to be obtained. This study aimed to estimate the predicted blood volume and CD34+ cell counts using collection efficiency (CE)-based formulas and evaluate their accuracy compared to the actual CD34+ cell counts. It also seeks to identify the factors that affect CE. Data from 397 healthy, unrelated stem cell donors were retrospectively analyzed. An algorithm using four different CE2 metrics (1st quartile, mean, 3rd quartile, and median) was developed to predict the volume of blood to be processed using the Spectra Optia continuous mononuclear cell collection procedure. When employing the mean CE2 algorithm, the results revealed a strong correlation (r = .894, p < .001) between predicted and actual CD34+ values. The study also identified strong associations between pre-apheresis CD34+, pre-apheresis leukocyte count, the use of two doses of G-CSF, and low CE2. These findings suggest that the mean CE2 algorithm could be a potent, straightforward, and accurate tool for predicting CD34+ stem cell counts in healthy allogeneic stem cell donors and potentially optimizing stem cell collection procedures.

High Resolution HLA-A, HLA-B, and HLA-C Allele Frequencies in Romanian Hematopoietic Stem Cell Donors.

The HLA genes are associated with various autoimmune pathologies, with the control of the immune response also being significant in organs and cells transplantation. The aim of the study is to identify the HLA-A, HLA-B, and HLA-C alleles frequencies in the analyzed Romanian cohort. We performed HLA typing using next-generation sequencing (NGS) in a Romanian cohort to estimate class I HLA allele frequencies up to a six-digit resolution. A total of 420 voluntary donors from the National Registry of Voluntary Hematopoietic Stem Cell Donors (RNDVCSH) were included in the study for HLA genotyping. Peripheral blood samples were taken and brought to the Fundeni Clinical Institute during 2020-2021. HLA genotyping was performed using the Immucor Mia Fora NGS MFlex kit. A total of 109 different alleles were detected in 420 analyzed samples, out of which 31 were for HLA-A, 49 for HLA-B, and 29 for HLA-C. The most frequent HLA-A alleles were HLA-A*02:01:01 (26.11%), HLA-A*01:01:01 (12.5%), HLA-A*24:02:01 (11.67%), HLA-A*03:01:01 (9.72%), HLA-A*11:01:01, and HLA-A*32:01:01 (each with 8.6%). For the HLA-B locus, the most frequent allele was HLA-B*18:01:01 (11.25%), followed by HLA-B*51:01:01 (10.83%) and HLA-B*08:01:01 (7.78%). The most common HLA-C alleles were HLA-C*07:01:01 (17.36%), HLA-C*04:01:01 (13.47%), and HLA-C*12:03:01 (10.69%). Follow-up studies are ongoing for confirming the detected results.

Studying Pathogenetic Contribution of a Variant of Unknown Significance, p.M659I (c.1977G > A) in MYH7, to the Development of Hypertrophic Cardiomyopathy Using CRISPR/Cas9-Engineered Isogenic Induced Pluripotent Stem Cells.

Hypertrophic cardiomyopathy (HCM) is a cardiovascular pathology that is caused by variants in genes encoding sarcomere-associated proteins. However, the clinical significance of numerous variants in HCM-associated genes is still unknown. CRISPR/Cas9 is a tool of nucleotide sequence editing that allows for the unraveling of different biological tasks. In this study, introducing a mutation with CRISPR/Cas9 into induced pluripotent stem cells (iPSCs) of a healthy donor and the directed differentiation of the isogenic iPSC lines into cardiomyocytes were used to assess the pathogenicity of a variant of unknown significance, p.M659I (c.1977G > A) in MYH7, which was found previously in an HCM patient. Using two single-stranded donor oligonucleotides with and without the p.M659I (c.1977G > A) mutation, together with CRISPR/Cas9, an iPSC line heterozygous at the p.M659I (c.1977G > A) variant in MYH7 was generated. No CRISPR/Cas9 off-target activity was observed. The iPSC line with the introduced p.M659I (c.1977G > A) mutation in MYH7 retained its pluripotent state and normal karyotype. Compared to the isogenic control, cardiomyocytes derived from the iPSCs with the introduced p.M659I (c.1977G > A) mutation in MYH7 recapitulated known HCM features: enlarged size, elevated diastolic calcium level, changes in the expression of HCM-related genes, and disrupted energy metabolism. These findings indicate the pathogenicity of the variant.