Expanded newborn screening (ENBS) utilizing tandem mass spectrometry (MS/MS) for inborn metabolic diseases (IMDs), such as organic acidemias (OAs), fatty acid oxidation disorders, (FAODs), and amino acid disorders (AAs), is increasingly popular but has not yet been introduced in many Asian countries. This study aimed to determine the incidence rates of OAs, FAODs, and AAs in Asian countries and Germany using selective screening and ENBS records. Selective screening for IMDs using gas chromatography-mass spectrometry and MS/MS was performed among patients suspected to be afflicted in Asian countries (including Japan, Vietnam, China, and India) between 2000 and 2015, and the results from different countries were compared. Similarly, ENBS results from Japan, South Korea, Taiwan, and Germany were compared. Additionally, the results of selective screening and ENBS in Japan were compared. Among 39,270 patients who underwent selective screening, IMDs were detected in 1170. Methylmalonic acidemia was frequently identified in several countries, including Japan (81/377 diagnosed IMDs), China (94/216 IMDs), and India (72/293 IMDs). In Vietnam, however, β-ketothiolase deficiency was particularly frequent (33/250 IMDs). ENBS yielded differences in overall IMD rates by country: 1:8557 in Japan, 1:7030 in Taiwan, 1:13,205 in South Korea, and 1:2200 in Germany. Frequently discovered diseases included propionic acidemia (PPA) and phenylketonuria (PKU) in Japan, 3-methylcrotonyl-CoA carboxylase deficiency (MCCD) and PKU in Taiwan, MCCD and citrullinemia type I in South Korea, and PKU and medium-chain acyl-CoA dehydrogenase deficiency in Germany. Furthermore, in Japan, selective screening and ENBS yielded respective PPA frequencies of 14.7% and 49.4% among all organic acidemias. The incidence rates of IMDs vary by country. Moreover, the disease spectra of IMDs detected via selective screening differ from those detected via ENBS.

Mitochondria are essential organelles for maintaining intracellular homeostasis. Their dysfunction can directly or indirectly affect cell functioning and is linked to multiple diseases. Donation of exogenous mitochondria is potentially a viable therapeutic strategy. For this, selecting appropriate donors of exogenous mitochondria is critical. We previously demonstrated that ultra-purified bone marrow-derived mesenchymal stem cells (RECs) have better stem cell properties and homogeneity than conventionally cultured bone marrow-derived mesenchymal stem cells. Here, we explored the effect of contact and noncontact systems on three possible mitochondrial transfer mechanisms involving tunneling nanotubes, connexin 43 (Cx43)-mediated gap junction channels (GJCs), and extracellular vesicles (Evs). We show that Evs and Cx43-GJCs provide the main mechanism for mitochondrial transfer from RECs. Through these two critical mitochondrial transfer pathways, RECs could transfer a greater number of mitochondria into mitochondria-deficient (ρ⁰) cells and could significantly restore mitochondrial functional parameters. Furthermore, we analyzed the effect of exosomes (EXO) on the rate of mitochondrial transfer from RECs and recovery of mitochondrial function. REC-derived EXO appeared to promote mitochondrial transfer and slightly improve the recovery of mtDNA content and oxidative phosphorylation in ρ⁰ cells. Thus, ultrapure, homogenous, and safe stem cell RECs could provide a potential therapeutic tool for diseases associated with mitochondrial dysfunction.

Patients with severe hypophosphatasia (HPP) develop osteogenic impairment with extremely low alkaline phosphatase (ALP) activity, resulting in a fatal course during infancy. Mesenchymal stem cells (MSCs) differentiate into various mesenchymal lineages, including bone and cartilage. The efficacy of allogeneic hematopoietic stem cell transplantation for congenital skeletal and storage disorders is limited, and therefore we focused on MSCs for the treatment of HPP. To determine the effect of MSCs on osteogenesis, we performed multiple infusions of ex vivo expanded allogeneic MSCs for two patients with severe HPP who had undergone bone marrow transplantation (BMT) from asymptomatic relatives harboring the heterozygous mutation. There were improvements in not only bone mineralization but also muscle mass, respiratory function, and mental development, resulting in the patients being alive at the age of 3. After the infusion of MSCs, chimerism analysis of the mesenchymal cell fraction isolated from bone marrow in the patients demonstrated that donor-derived DNA sequences existed. Adverse events of BMT were tolerated, whereas those of MSC infusion did not occur. However, restoration of ALP activity was limited, and normal bony architecture could not be achieved. Our data suggest that multiple MSC infusions, following BMT, were effective and brought about clinical benefits for patients with lethal HPP. Allogeneic MSC-based therapy would be useful for patients with other congenital bone diseases and tissue disorders if the curative strategy to restore clinically normal features, including bony architecture, can be established.

Background: Mitochondrial dysfunction caused by mutations in mitochondrial DNA (mtDNA) or nuclear DNA, which codes for mitochondrial components, are known to be associated with various genetic and congenital disorders. These mitochondrial disorders not only impair energy production but also affect mitochondrial functions and have no effective treatment. Mesenchymal stem cells (MSCs) are known to migrate to damaged sites and carry out mitochondrial transfer. MSCs grown using conventional culture methods exhibit heterogeneous cellular characteristics. In contrast, highly purified MSCs, namely the rapidly expanding clones (RECs) isolated by single-cell sorting, display uniform MSCs functionality. Therefore, we examined the differences between RECs and MSCs to assess the efficacy of mitochondrial transfer. Methods: We established mitochondria-deficient cell lines (ρ⁰ A549 and ρ⁰ HeLa cell lines) using ethidium bromide. Mitochondrial transfer from RECs/MSCs to ρ⁰ cells was confirmed by PCR and flow cytometry analysis. We examined several mitochondrial functions including ATP, reactive oxygen species, mitochondrial membrane potential, and oxygen consumption rate (OCR). The route of mitochondrial transfer was identified using inhibition assays for microtubules/tunneling nanotubes, gap junctions, or microvesicles using transwell assay and molecular inhibitors. Results: Co-culture of ρ⁰ cells with MSCs or RECs led to restoration of the mtDNA content. RECs transferred more mitochondria to ρ⁰ cells compared to that by MSCs. The recovery of mitochondrial function, including ATP, OCR, mitochondrial membrane potential, and mitochondrial swelling in ρ⁰ cells co-cultured with RECs was superior than that in cells co-cultured with MSCs. Inhibition assays for each pathway revealed that RECs were sensitive to endocytosis inhibitor, dynasore. Conclusions: RECs might serve as a potential therapeutic strategy for diseases linked to mitochondrial dysfunction by donating healthy mitochondria.