Fetal Kidney Grafts and Organoids from Microminiature Pigs: Establishing a Protocol for Production and Long-Term Cryopreservation.

Fetal organs and organoids are important tools for studying organ development. Recently, porcine organs have garnered attention as potential organs for xenotransplantation because of their high degree of similarity to human organs. However, to meet the prompt demand for porcine fetal organs by patients and researchers, effective methods for producing, retrieving, and cryopreserving pig fetuses are indispensable. Therefore, in this study, to collect fetuses for kidney extraction, we employed cesarean sections to preserve the survival and fertility of the mother pig and a method for storing fetal kidneys by long-term cryopreservation. Subsequently, we evaluated the utility of these two methods. We confirmed that the kidneys of pig fetuses retrieved by cesarean section that were cryopreserved for an extended period could resume renal growth when grafted into mice and were capable of forming renal organoids. These results demonstrate the usefulness of long-term cryopreserved fetal pig organs and strongly suggest the effectiveness of our comprehensive system of pig fetus retrieval and fetal organ preservation, thereby highlighting its potential as an accelerator of xenotransplantation research and clinical innovation.

Exploration of Preservation Methods for Utilizing Porcine Fetal-Organ-Derived Cells in Regenerative Medicine Research.

Human pluripotent stem cells have been employed in generating organoids, yet their immaturity compared to fetal organs and the limited induction of all constituent cell types remain challenges. Porcine fetal progenitor cells have emerged as promising candidates for co-culturing with human progenitor cells in regeneration and xenotransplantation research. This study focused on identifying proper preservation methods for porcine fetal kidneys, hearts, and livers, aiming to optimize their potential as cell sources. Extracted from fetal microminiature pigs, these organs were dissociated before and after cryopreservation-thawing, with subsequent cell quality evaluations. Kidney cells, dissociated and aggregated after vitrification in a whole-organ form, were successfully differentiated into glomeruli and tubules in vivo. In contrast, freezing hearts and livers before dissociation yielded suboptimal results. Heart cells, frozen after dissociation, exhibited pulsating heart muscle cells similar to non-frozen hearts. As for liver cells, we developed a direct tissue perfusion technique and successfully obtained highly viable liver parenchymal cells. Freezing dissociated liver cells, although inferior to their non-frozen counterparts, maintained the ability for colony formation. The findings of this study provide valuable insights into suitable preservation methods for porcine fetal cells from kidneys, hearts, and livers, contributing to the advancement of regeneration and xenotransplantation research.

Maturation and development of fetal pig intestinal tissue in immunodeficient mice.

PURPOSE: This study aimed to compare the degree of maturation and development of fetal pig segmental intestinal tissue with that of spheroids created by in-vitro reaggregation of dissociated fetal intestinal cells after transplantation into immunodeficient mice. METHODS: Fetal pig small intestines were transplanted as segmental grafts into the omentum and subrenal capsules of immunodeficient mice or enzymatically treated to generate single cells. Spheroids made by in-vitro reaggregation of these cells were transplanted into the subrenal capsules of immunodeficient mice. The segmental grafts and spheroids were harvested four and eight weeks after transplantation, and the structural maturity and in-vivo development of these specimens were histologically evaluated. RESULTS: The spheroids were engrafted and supplied blood vessels from the host mice, but an intestinal layered structure was not clearly observed, and there was almost no change in size. On the other hand, the segmental grafts formed deep crypts in the mucus membrane, the inner circular layer, and outer longitudinal muscles. The crypts of the transplanted grafts harvested at eight weeks were much deeper, and the smooth muscle layer and the enteric nervous system were more mature than those of grafts harvested at the fourth week, although the intestinal peristaltic wave was not observed. CONCLUSIONS: Spheroids created from fetal small intestinal cells could not form layered structures or mature sufficiently. Conversely, segmental tissues structurally matured and developed after in-vivo transplantation and are therefore potential grafts for transplantation.

Maturation and development of fetal pig intestinal tissue in immunodeficient mice

Purpose: This study aimed to compare the degree of maturation and development of fetal pig segmental intestinal tissue with that of spheroids created by in-vitro reaggregation of dissociated fetal intestinal cells after transplantation into immunodeficient mice. Methods: Fetal pig small intestines were transplanted as segmental grafts into the omentum and subrenal capsules of immunodeficient mice or enzymatically treated to generate single cells. Spheroids made by in-vitro reaggregation of these cells were transplanted into the subrenal capsules of immunodeficient mice. The segmental grafts and spheroids were harvested four and eight weeks after transplantation, and the structural maturity and in-vivo development of these specimens were histologically evaluated. Results: The spheroids were engrafted and supplied blood vessels from the host mice, but an intestinal layered structure was not clearly observed, and there was almost no change in size. On the other hand, the segmental grafts formed deep crypts in the mucus membrane, the inner circular layer, and outer longitudinal muscles. The crypts of the transplanted grafts harvested at eight weeks were much deeper, and the smooth muscle layer and the enteric nervous system were more mature than those of grafts harvested at the fourth week, although the intestinal peristaltic wave was not observed. Conclusions: Spheroids created from fetal small intestinal cells could not form layered structures or mature sufficiently. Conversely, segmental tissues structurally matured and developed after in-vivo transplantation and are therefore potential grafts for transplantation.

Long-term viable chimeric nephrons generated from progenitor cells are a reliable model in cisplatin-induced toxicity.

Kidney organoids have shown promise as evaluation tools, but their in vitro maturity remains limited. Transplantation into adult mice has aided in maturation; however, their lack of urinary tract connection limits long-term viability. Thus, long-term viable generated nephrons have not been demonstrated. In this study, we present an approachable method in which mouse and rat renal progenitor cells are injected into the developing kidneys of neonatal mice, resulting in the generation of chimeric nephrons integrated with the host urinary tracts. These chimeric nephrons exhibit similar maturation to the host nephrons, long-term viability with excretion and reabsorption functions, and cisplatin-induced renal injury in both acute and chronic phases, as confirmed by single-cell RNA-sequencing. Additionally, induced human nephron progenitor cells differentiate into nephrons within the neonatal kidneys. Collectively, neonatal injection represents a promising approach for in vivo nephron generation, with potential applications in kidney regeneration, drug screening, and pathological analysis.

Evaluation of the ability of human induced nephron progenitor cells to form chimeric renal organoids using mouse embryonic renal progenitor cells.

The number of patients with end-stage renal failure is increasing annually worldwide and the problem is compounded by a shortage of renal transplantation donors. In our previous research, we have shown that transplantation of renal progenitor cells into the nephrogenic region of heterologous fetuses can induce the development of nephrons. We have also developed transgenic mice in which specific renal progenitor cells can be removed by drugs. By combining these two technologies, we have succeeded in generating human-mouse chimeric kidneys in fetal mice. We hope to apply these technologies to regenerative medicine. The quality of nephron progenitor cells (NPCs) derived from human pluripotent stem cells is important for the generation of chimeric kidneys, but there is currently no simple evaluation system for the chimerogenic potential of human NPCs. In this study, we focused on the fact that the re-aggregation of mouse renal progenitor cells can be used for nephron formation, even when merged into single cells. First, we examined the conditions under which nephron formation is likely to occur in mice during re-aggregation. Next, to improve the differentiation potential of human NPCs derived from pluripotent stem cells, NPCs were sorted using Integrin subunit alpha 8 (ITGA8). Finally, we demonstrated chimera formation between different species by mixing mouse cells with purified, selectively-induced human NPCs under optimum conditions. We observed these chimeric organoids at different time points to learn about these human-mouse chimeric structures at various stages of renal development. We found that the rate of chimera formation was affected by the purity of the human NPCs and the cell ratios used. We demonstrated that chimeric nephrons can be generated using a simple model, even between distant species. We believe that this admixture of human and mouse renal progenitor cells is a promising technology with potential application for the evaluation of the chimera formation abilities of NPCs.

Cryopreservation of Fetal Porcine Kidneys for Xenogeneic Regenerative Medicine.

Kidney xenotransplantation has been attracting attention as a treatment option for end-stage renal disease. Fetal porcine kidneys are particularly promising grafts because they can reduce rejection through vascularization from host vessels. We are proposing xenogeneic regenerative medicine using fetal porcine kidneys injected with human nephron progenitor cells. For clinical application, it is desirable to establish reliable methods for the preservation and quality assessment of grafts. We evaluated the differentiation potency of vitrified porcine fetal kidneys compared with nonfrozen kidneys, using an in vivo differentiation model. Fetal porcine kidneys connected to the bladder were frozen via vitrification and stored in liquid nitrogen. Several days later, they were thawed and transplanted under the retroperitoneum of immunocompromised mice. After 14 days, the frozen kidneys grew and differentiated into mature nephrons, and the findings were comparable to those of nonfrozen kidneys. In conclusion, we demonstrated that the differentiation potency of vitrified fetal porcine kidneys could be evaluated using this model, thereby providing a practical protocol to assess the quality of individual lots.

Experience with enteral sulfonylurea monotherapy for extremely low birth weight infants with hyperglycemia.

Limited data are available on the effects of enteral sulfonylurea (SU) monotherapy in extremely low birth weight infants (ELBWIs) with hyperglycemia. Therefore, we report our experience with enteral SU monotherapy for hyperglycemic ELBWIs. We retrospectively evaluated 11 hyperglycemic ELBWIs (seven male infants, median gestational age = 24.9 wk) who received SU between January 2016 and December 2019. Blood glucose (BG) levels were monitored before and after SU initiation and evaluated for the occurrence of adverse effects. We administered SU at a median of 15 d (interquartile range [IQR]: 12-20 d) after birth, with the median maximum dose of 0.2 mg/kg/d (IQR: 0.125-0.3 mg/kg/d). Hyperglycemia improved in all patients, and the target BG levels were achieved without severe side effects at a median of 6 d (IQR: 4-8.5 d) after initiation of treatment. The incidence of hypoglycemia during SU treatment was observed in 18 events per 1000 patient hours; however, the patients were asymptomatic. Based on these results, enteral SU monotherapy may be considered as an option for hyperglycemic ELBWIs.

Risk factors for hyperglycemia in extremely low birth weight infants during the first 14 days.

BACKGROUND: There are limited data regarding the risk factors for hyperglycemia in extremely low birth weight infants (ELBWIs). The aim of this observational study was to investigate the incidence of hyperglycemia among ELBWIs during the first 14 days of life and identify independent risk factors for hyperglycemia development. METHODS: We retrospectively evaluated 55 ELBWIs (32 male infants) between January 2015 and March 2020. Hyperglycemia was diagnosed when the glucose level was ≥180 mg/dL. Demographic and clinical data were extracted from the patients' medical records. The risk factors associated with the onset of hyperglycemia were identified by Cox proportional hazards regression analysis with variables that had previously been identified as risk factors for hyperglycemia. RESULTS: Hyperglycemia developed in 23 patients (41.8%) within the first 14 days of life. Gestational age, chorioamnionitis, postnatal intravenous glucocorticoids, and probiotic type were included in the analysis. The results indicated that hyperglycemia was significantly associated with gestational age (hazard ratio [HR], 0.65; 95% confidence interval [CI], 0.48-0.87; P = 0.004). Further, Bifidobacterium breve (B. breve M-16V) use was related to hyperglycemia in ELBWIs (HR, 2.95; 95% CI, 1.10-7.87; P = 0.031). CONCLUSION: Hyperglycemia was strongly associated with lower gestational age and B. breve M-16V use in our study population. Although probiotic supplementation may be beneficial for preterm infants to reduce the incidence of necrotizing enterocolitis, the dextrin used as an excipient in B. breve M-16V may lead to an undesirable carbohydrate load in ELBWIs.

Characterization of a Small Supernumerary Marker Chromosome Derived from Xq28 and 14q11.2 Detected Prenatally.

We present the characterization of a case with a small supernumerary marker chromosome (sSMC) detected prenatally derived from Xq28 and 14q11.2 maternal translocation. A 33-year-old Japanese woman, primigravida, underwent amniocentesis because of fetal growth restriction and fetal structural abnormality at 30 weeks of gestation. The fetal karyotype was identified as 47,XY,+mar. Additionally, the single nucleotide polymorphism array analysis revealed copy number gains at Xq28 and 14q11.2. A male infant, weighing 1,391 g, was delivered at term by cesarean section. Maternal and paternal karyotypes were 46,X,t(X; 14)(q28; q11) and 46,XY, respectively. These findings indicated that the sSMC might have originated from chromosome disjunction at a ratio of three to one. Here we describe a case with an sSMC derived from Xq28 and 14q11.2. Our findings suggest that this sSMC is most likely pathogenic. The collection of additional cases may be required.

[Maternal Crohn's disease-related vitamin B12 deficient megaloblastic anemia in an infant].

We report an 11-month-old breast-fed boy with feeding difficulties, lethargy, and developmental delay. Blood examination showed pancytopenia and decreased serum levels of vitamin B12. Anisocytosis and poikilocytes were detected in his peripheral blood, and increased megaloblastosis without leukemic cells was detected in his bone marrow. After the diagnosis of megaloblastic anemia due to vitamin B12 deficiency, symptoms were improved by vitamin B12 administration. Further investigation of the mother identified Crohn's disease and suggested that the supply of vitamin B12 from the mother to the infant, via the placenta during pregnancy and via breast milk after birth, was decreased due to impaired absorption of vitamin B12 in the mother's small intestine. Magnetic resonance imaging of the boy's brain on admission showed cerebral cortex atrophy which had improved by the age of 1 year and 10 months after vitamin B12 treatment, though developmental delay was still evident at the age of 3 years. Infantile vitamin B12 deficiency often presents with nonspecific manifestations, such as developmental delay and failure to thrive, in addition to anemia and is thus not easily diagnosed. To prevent severe neurological sequelae, this condition must be rapidly diagnosed, because a prolonged duration increases the risk of permanent disabilities.