Comparison of retinal degeneration treatment with four types of different mesenchymal stem cells, human induced pluripotent stem cells and RPE cells in a rat retinal degeneration model.

BACKGROUND: Retinal degeneration (RD) is a group of disorders on irreversible vision loss. Multiple types of stem cells were used in clinical trials for RD treatment. However, it remains unknown what kinds of stem cells are most effective for the treatment. Therefore, we investigated the subretinal transplantation of several types of stem cells, human adipose-derived stem cells (hADSCs), amniotic fluid stem cells (hAFSCs), bone marrow stem cells (hBMSCs), dental pulp stem cells (hDPSCs), induced pluripotent stem cell (hiPSC), and hiPSC-derived retinal pigment epithelium (RPE) cells for protection effects, paracrine effects and treatment efficiency in an RD disease model rats. METHODS: The generation and characterization of these stem cells and hiPSC-derived RPE cells were performed before transplantation. The stem cells or hiPSC-derived RPE cell suspension labelled with CellTracker Green to detect transplanted cells were delivered into the subretinal space of 3-week-old RCS rats. The control group received subretinal PBS injection or non-injection. A series of detections including fundus photography, optomotor response (OMR) evaluations, light-dark box testing, electroretinography (ERG), and hematoxylin and eosin (HE) staining of retinal sections were conducted after subretinal injection of the cells. RESULTS: Each stem cell, hiPSC-derived RPE cell or PBS (blank experiment) was successfully transplanted into at least six RCS rats subretinally. Compared with the control rats, RCS rats subjected to subretinal transplantation of any stem cells except hiPSCs showed higher ERG waves (p < 0.05) and quantitative OMR (qOMR) index values (hADSCs: 1.166, hAFSCs: 1.249, hBMSCs: 1.098, hDPSCs: 1.238, hiPSCs: 1.208, hiPSC-RPE cells: 1.294, non-injection: 1.03, PBS: 1.06), which indicated better visual function, at 4 weeks post-injection. However, only rats that received hiPSC-derived RPE cells maintained their visual function at 8 weeks post-injection (p < 0.05). The outer nuclear layer thickness observed in histological sections after HE staining showed the same pattern as the ERG and qOMR results. CONCLUSIONS: Compared to hiPSC-derived RPE cells, adult and fetal stem cells yielded improvements in visual function for up to 4 weeks post-injection; this outcome was mainly based on the paracrine effects of several types of growth factors secreted by the stem cells. Patients with RD will benefit from the stem cell therapy.

Antibody Profiling of Kawasaki Disease Using Escherichia coli Proteome Microarrays.

Kawasaki disease (KD) is a form of systemic vasculitis that generally occurs in children under 5 years old. Currently, KD is still diagnosed according to its clinical symptoms, including prolonged fever, skin rash, conjunctivitis, neck lymphadenopathy, palm erythema, and oral mucosa changes. Because KD is a type of inflammation without specific marker for diagnosis, we plan to profile the plasma antibodies by using E. coli proteome microarray and analyze the differences between KD and healthy subjects. Plasmas were collected from KD patient before intravenous immunoglobulin treatment (KD1), at least 3 weeks after treatment (KD3), nonfever control (NC), and fever control (FC) children. The initial screening, which consisted of 20 KD1, 20 KD3, 20 NC, and 20 FC, were explored using E. coli proteome microarrays (∼4200 unique proteins). About ∼70 proteins were shown to have high accuracy, e.g. 0.78∼0.92, with regard to separating KD1, KD3, NC, and FC. Those proteins were then purified to fabricate KD focus arrays for training (n = 20 each) and blind-testing (n = 20 each). It only took 125 pl of plasma, less than a drop of blood, in the focus array assays. The AUC scores for blind tests of KD1 versus NC (17 protein markers), KD1 versus FC (20 protein markers), KD3 versus NC (9 protein markers), and KD1 versus KD3 (6 protein markers) were 0.84, 0.75, 0.99 and 0.98, respectively. This study is the first to profile plasma antibodies in KD and demonstrate that an E. coli proteome microarray can screen differences among patients with KD, nonfever controls, and fever controls.

Escherichia coli Proteome Microarrays Identified the Substrates of ClpYQ Protease.

Proteolysis is a vital mechanism to regulate the cellular proteome in all kingdoms of life, and ATP-dependent proteases play a crucial role within this process. In Escherichia coli, ClpYQ is one of the primary ATP-dependent proteases. In addition to function with removals of abnormal peptides in the cells, ClpYQ degrades regulatory proteins if necessary and thus let cells adjust to various environmental conditions. In E. coli, SulA, RcsA, RpoH and TraJ as well as RNase R, have been identified as natural protein substrates of ClpYQ. ClpYQ contains ClpY and ClpQ. The ATPase ClpY is responsible for protein recognition, unfolding, and translocation into the catalytic core of ClpQ. In this study, we use an indirect identification strategy to screen possible ClpY targets with E. coli K12 proteome chips. The chip assay results showed that YbaB strongly bound to ClpY. We used yeast two-hybrid assay to confirm the interactions between ClpY and YbaB protein and determined the Kd between ClpY and YbaB by quartz crystal microbalance. Furthermore, we validated that YbaB was successfully degraded by ClpYQ protease activity using ClpYQ in vitro and in vivo degradation assay. These findings demonstrated the YbaB is a novel substrate of ClpYQ protease. This work also successfully demonstrated that with the use of recognition element of a protease can successfully screen its substrates by indirect proteome chip screening assay.

Lactoferricin B inhibits the phosphorylation of the two-component system response regulators BasR and CreB.

Natural antimicrobial peptides provide fundamental protection for multicellular organisms from microbes, such as Lactoferricin B (Lfcin B). Many studies have shown that Lfcin B penetrates the cell membrane and has intracellular activities. To elucidate the intracellular behavior of Lfcin B, we first used Escherichia coli K12 proteome chips to identify the intracellular targets of Lfcin B. The results showed that Lfcin B binds to two response regulators, BasR and CreB, of the two-component system. For further analysis, we conducted several in vitro and in vivo experiments and utilized bioinformatics methods. The electrophoretic mobility shift assays and kinase assays indicate that Lfcin B inhibits the phosphorylation of the response regulators (BasR and CreB) and their cognate sensor kinases (BasS and CreC). Antibacterial assays showed that Lfcin B reduced E. coli's tolerance to environmental stimuli, such as excessive ferric ions and minimal medium conditions. This is the first study to show that an antimicrobial peptide inhibits the growth of bacteria by influencing the phosphorylation of a two-component system directly.

Lipid nanoparticle technology-mediated therapeutic gene manipulation in the eyes.

Millions of people worldwide have hereditary genetic disorders, trauma, infectious diseases, or cancer of the eyes, and many of these eye diseases lead to irreversible blindness, which is a major public health burden. The eye is a relatively small and immune-privileged organ. The use of nucleic acid-based drugs to manipulate malfunctioning genes that target the root of ocular diseases is regarded as a therapeutic approach with great promise. However, there are still some challenges for utilizing nucleic acid therapeutics in vivo because of certain unfavorable characteristics, such as instability, biological carrier-dependent cellular uptake, short pharmacokinetic profiles in vivo (RNA), and on-target and off-target side effects (DNA). The development of lipid nanoparticles (LNPs) as gene vehicles is revolutionary progress that has contributed the clinical application of nucleic acid therapeutics. LNPs have the capability to entrap and transport various genetic materials such as small interfering RNA, mRNA, DNA, and gene editing complexes. This opens up avenues for addressing ocular diseases through the suppression of pathogenic genes, the expression of therapeutic proteins, or the correction of genetic defects. Here, we delve into the cutting-edge LNP technology for ocular gene therapy, encompassing formulation designs, preclinical development, and clinical translation.

Design and lyophilization of mRNA-encapsulating lipid nanoparticles.

The remarkable success of two FDA-approved mRNA-encapsulating vaccines (Comirnaty® and Spikevax®) indicated the importance of lipid nanoparticles (LNPs) delivery systems in clinical use. Currently, mRNA-encapsulating LNPs (mRNA-LNPs) vaccines are stored as frozen liquid at low or ultralow temperatures. We designed lyophilized LNPs utilizing FDA-approved lipids to expedite the clinical application of our developed lyophilized mRNA-LNPs in the future. The key parameters of sucrose concentration and the selection and molar ratio of the four lipids in these vaccines were optimized for long-term stability with high transfection efficiency after lyophilization. We demonstrated that 8.7% sucrose is the optimal cryoprotectant concentration to maintain the transfection efficiency of lyophilized mRNA-LNPs. Optimal lipid formulations with high transfection efficiency both before and after lyophilization were screened using an orthogonal experimental design. The ratios of distearoylphosphatidylcholine (DSPC)/cholesterol and the selection of the ionizable and PEGylated lipids are the main factors influencing the long-term stability of mRNA-LNPs. Comparative mouse transfection experiments showed that the optimal lyophilized mRNA-LNPs maintained high mRNA expression after lyophilization, predominantly in the spleen or liver, with no expression in the kidneys or eyes. Our studies demonstrated the importance of the sucrose concentration and of the selection and molar ratio of the four lipids composing LNPs for maintaining mRNA-LNP stability under lyophilization and for long-term storage under mild conditions.

Effects of ECM protein-coated surfaces on the generation of retinal pigment epithelium cells differentiated from human pluripotent stem cells.

Retinal degeneration diseases, such as age-related macular degeneration (AMD) and retinitis pigmentosa (RP), initially manifest as dysfunction or death of the retinal pigment epithelium (RPE). Subretinal transplantation of human pluripotent stem cell (hPSC)-derived RPE cells has emerged as a potential therapy for retinal degeneration. However, RPE cells differentiated from hPSCs using current protocols are xeno-containing and are rarely applied in clinical trials. The development of hPSC-derived RPE cell differentiation protocols using xeno-free biomaterials is urgently needed for clinical applications. In this study, two protocols (the activin A and NIC84 protocols) were selected for modification and use in the differentiation of hiPSCs into RPE cells; the chetomin concentration was gradually increased to achieve high differentiation efficiency of RPE cells. The xeno-free extracellular matrix (ECM) proteins, laminin-511, laminin-521 and recombinant vitronectin, were selected as plate-coating substrates, and a Matrigel (xeno-containing ECM)-coated surface was used as a positive control. Healthy, mature hPSC-derived RPE cells were transplanted into 21-day-old Royal College of Surgeons (RCS) rats, a model of retinal degeneration disease. The visual function of RCS rats was evaluated by optomotor response (qOMR) and electroretinography after transplantation of hPSC-derived RPE cells. Our study demonstrated that hPSCs can be efficiently differentiated into RPE cells on LN521-coated dishes using the NIC84 protocol, and that subretinal transplantation of the cell suspensions can delay the progression of vision loss in RCS rats.

Design of dual peptide-conjugated hydrogels for proliferation and differentiation of human pluripotent stem cells.

Completely synthetic cell cultivation materials for human pluripotent stem cells (hPSCs) are important for the future clinical use of hPSC-derived cells. Currently, cell culture materials conjugated with extracellular matrix (ECM)-derived peptides are being prepared using only one specific integrin-targeting peptide. We designed dual peptide-conjugated hydrogels, for which each peptide was selected from different ECM sites: the laminin ß4 chain and fibronectin or vitronectin, which can target α6ß1 and α2ß1 or αVß5. hPSCs cultured on dual peptide-conjugated hydrogels, especially on hydrogels conjugated with peptides obtained from the laminin ß4 chain and vitronectin with a low peptide concentration of 200 µg/mL, showed high proliferation ability over the long term and differentiated into cells originating from 3 germ layers in vivo as well as a specific lineage of cardiac cells. The design of grafting peptides was also important, for which a joint segment and positive amino acids were added into the designed peptide. Because of the designed peptides on the hydrogels, only 200 µg/mL peptide solution was sufficient for grafting on the hydrogels, and the hydrogels supported hPSC cultures long-term; in contrast, in previous studies, greater than 1000 µg/mL peptide solution was needed for the grafting of peptides on cell culture materials.

Universal and hypoimmunogenic pluripotent stem cells for clinical usage.

It is urgent to prepare and store large numbers of clinical trial grade human pluripotent stem (hPS) cells for off-the-shelf use in stem cell therapies. However, stem cell banks, which store off-the-shelf stem cells, need financial support and large amounts of technicians for daily cell maintenance. Therefore, it is valuable to create "universal" or "hypoimmunogenic" hPS cells with genome editing engineering by knocking in or out immune-related genes. Only a small number of universal or hypoimmunogenic hPS cell lines should be needed to store for off-the-shelf usage and reduce the large amounts of instruments, consumables and technicians. In this article, we consider how to create hypoimmunogenic or universal hPS cells as well as the demerits of the technology. ß2-Microglobulin-knockout hPS cells did not harbor human leukocyte antigen (HLA)-expressing class I cells but led to the activation of natural killer cells. To escape the activities of macrophages and natural killer cells, homozygous hPS cells having a single allele of an HLA class I gene, such as HLA-C, were proposed. Major HLA class Ia molecules were knocked out, and CD47, HLA-G and PD-L1 were knocked in hPS cells utilizing CRISPR/Cas9 genome editing. Finally, some researchers are trying to generate universal hPS cells without genome editing. The cells evaded the activation of not only T cells but also macrophages and natural killer cells. These universal hPS cells have high potential for application in cell therapy.

Cell-binding peptides on the material surface guide stem cell fate of adhesion, proliferation and differentiation.

Human cells, especially stem cells, need to communicate and interact with extracellular matrix (ECM) proteins, which not only serve as structural components but also guide and support cell fate and properties such as cell adhesion, proliferation, survival and differentiation. The binding of the cells with ECM proteins or ECM-derived peptides via cell adhesion receptors such as integrins activates several signaling pathways that determine the cell fate, morphological change, proliferation and differentiation. The development of synthetic ECM protein-derived peptides that mimic the biological and biochemical functions of natural ECM proteins will benefit academic and clinical application. Peptides derived from or inspired by specific ECM proteins can act as agonists of each ECM protein receptor. Given that most ECM proteins function in cell adhesion via integrin receptors, many peptides have been developed that bind to specific integrin receptors. In this review, we discuss the peptide sequence, immobilization design, reaction method, and functions of several ECM protein-derived peptides. Various peptide sequences derived from mainly ECM proteins, which are used for coating or grafting on dishes, scaffolds, hydrogels, implants or nanofibers, have been developed to improve the adhesion, proliferation or differentiation of stem cells and to culture differentiated cells. This review article will help to inform the optimal choice of ECM protein-derived peptides for the development of scaffolds, implants, hydrogels, nanofibers and 2D cell culture dishes to regulate the proliferation and direct the differentiation of stem cells into specific lineages.

Next-generation materials for RNA-lipid nanoparticles: lyophilization and targeted transfection.

RNA, including mRNA, siRNA and miRNA, is part of a new class of patient treatments that prevent and treat several diseases. As an alternative to DNA therapy using plasmid DNA, RNA functions in the cellular cytosol, avoiding the potential risks of insertion into patient genomes. RNA drugs, including mRNA vaccines, need carrier materials for delivery into the patient's body. Several delivery carriers of mRNA, such as cationic polymers, lipoplexes, lipid-polymer nanoparticles and lipid nanoparticles (LNPs), have been investigated. For clinical applications, one of the most commonly selected types of RNA delivery carrier is LNPs, which are typically formed with (a) ionizable lipids, which bind to RNA; (b) cholesterol for stabilization; (c) phospholipids to form the LNPs; and (d) polyethylene glycol-conjugated lipids to prevent aggregation and provide stealth characteristics. Most RNA-LNP research has been devoted to achieving highly efficient RNA expression in vitro and in vivo. It is also necessary to study the extended storage of RNA-LNPs under mild conditions. One of the most efficient methods to store RNA-LNPs for a long time is to prepare freeze-dried (lyophilized) RNA-LNPs. Future research should include investigating LNP materials for the development of freeze-dried RNA-LNPs using optimal lipid components and compositions with optimal cryoprotectants. Furthermore, the development of sophisticated RNA-LNP materials for targeted transfection into specific tissues, organs or cells will be a future direction in the development RNA therapeutics. We will discuss the prospects for the development of next-generation RNA-LNP materials.

Designed peptide-grafted hydrogels for human pluripotent stem cell culture and differentiation.

Human pluripotent stem cells (hPSCs) have the ability to differentiate into cells derived from three germ layers and are an attractive cell source for cell therapy in regenerative medicine. However, hPSCs cannot be cultured on conventional tissue culture flasks but can be cultured on biomaterials with specific hPSC integrin interaction sites. We designed hydrogels conjugated with several designed peptides that had laminin-ß4 active sites, optimal elasticities and different zeta potentials. A higher expansion fold of hPSCs cultured on the hydrogels was found with the increasing zeta potential of the hydrogels conjugated with designed peptides, where positive amino acid (lysine) insertion into the peptides promoted higher zeta potentials of the hydrogels and higher expansion folds of hPSCs when cultured on the hydrogels using xeno-free protocols. The hPSCs cultured on hydrogels conjugated with the optimal peptides showed a higher expansion fold than those on recombinant vitronectin-coated plates, which are the gold standard of hPSC cultivation dishes. The hPSCs could differentiate into specific cell lineages, such as mesenchymal stem cells (MSCs) and MSC-derived osteoblasts, even after being cultivated on hydrogels conjugated with optimal peptides for long periods of time, such as 10 passages.

Neuronal Cell Differentiation of Human Dental Pulp Stem Cells on Synthetic Polymeric Surfaces Coated With ECM Proteins.

Stem cells serve as an ideal source of tissue regeneration therapy because of their high stemness properties and regenerative activities. Mesenchymal stem cells (MSCs) are considered an excellent source of stem cell therapy because MSCs can be easily obtained without ethical concern and can differentiate into most types of cells in the human body. We prepared cell culture materials combined with synthetic polymeric materials of poly-N-isopropylacrylamide-co-butyl acrylate (PN) and extracellular matrix proteins to investigate the effect of cell culture biomaterials on the differentiation of dental pulp stem cells (DPSCs) into neuronal cells. The DPSCs cultured on poly-L-ornithine (PLO)-coated (TPS-PLO) plates and PLO and PN-coated (TPS-PLO-PN) plates showed excellent neuronal marker (ßIII-tubulin and nestin) expression and the highest expansion rate among the culture plates investigated in this study. This result suggests that the TPS-PLO and TPS-PN-PLO plates maintained stable DPSCs proliferation and had good capabilities of differentiating into neuronal cells. TPS-PLO and TPS-PN-PLO plates may have high potentials as cell culture biomaterials for the differentiation of MSCs into several neural cells, such as cells in the central nervous system, retinal cells, retinal organoids and oligodendrocytes, which will expand the sources of cells for stem cell therapies in the future.

Effect of extracellular matrix proteins on the differentiation of human pluripotent stem cells into mesenchymal stem cells.

The transplantation of human mesenchymal stem cells (hMSCs), such as bone marrow stem cells (BMSCs) and adipose-derived stem cells (ADSCs), has shown beneficial effects in protecting transplanted tissues and cells against graft-versus-host disease (GVHD). Human pluripotent stem cell (hPSC)-derived mesenchymal stem cells (MSCs) can also be used to generate hMSCs with stable characteristics without limitations. Therefore, we differentiated human induced pluripotent stem cells (hiPSCs, H-M5) and human embryonic stem cells (hESCs, H9) into hMSCs on dishes coated with different extracellular matrix (ECM) proteins to study the effect of cell culture biomaterials on hPSC differentiation into hMSCs. hPSC-derived MSCs cultured on Matrigel (MAT)-coated, collagen (COL)-coated and laminin-521 (LN-521)-coated tissue culture polystyrene (TCP) dishes showed excellent proliferation speed and reduced aging over 10 passages. High MSC surface marker (CD44, CD73, CD90 and CD105) expression was also observed on hPSC-derived MSCs cultured on MAT-coated, COL-coated and LN-521-coated TCP dishes as well as uncoated TCP dishes. Analysis of late osteogenic differentiation by evaluation of mineral deposition revealed that hPSC-derived MSCs cultured on fibronectin (FN)-coated and LN-521-coated TCP dishes showed high osteogenic differentiation. ECM proteins are effective as coating materials on cell culture biomaterials to regulate the proliferation and differentiation fate of hPSC-derived MSCs.

Poly(vinyl alcohol-co-itaconic acid) hydrogels grafted with several designed peptides for human pluripotent stem cell culture and differentiation into cardiomyocytes.

We developed poly(vinyl alcohol-co-itaconic acid) (PV) hydrogels grafted with laminin-derived peptides that had different joint segments and several specific designs, including dual chain motifs. PV hydrogels grafted with a peptide derived from laminin-ß4 (PMQKMRGDVFSP) containing a joint segment, dual chain motif and cationic amino acid insertion could attach human pluripotent stem (hPS) cells and promoted high expansion folds in long-term culture (over 10 passages) with low differentiation rates, whereas hPS cells attached poorly on PV hydrogels grafted with laminin-α5 peptides that had joint segments with and without a cationic amino acid or on PV hydrogels grafted with laminin-ß4 peptides containing the joint segment only. The inclusion of a cationic amino acid in the laminin-ß4 peptide was critical for hPS cell attachment on PV hydrogels, which contributed to the zeta potential shifting to higher values (3-4 mV enhancement). The novel peptide segment-grafted PV hydrogels developed in this study supported hPS cell proliferation, which induced better hPS cell expansion than recombinant vitronectin-coated dishes (gold standard of hPS cell culture dishes) in xeno-free culture conditions. After long-term culture on peptide-grafted hydrogels, hPS cells could be induced to differentiate into specific lineages of cells, such as cardiomyocytes, with high efficiency.

Transient characteristics of universal cells on human-induced pluripotent stem cells and their differentiated cells derived from foetal stem cells with mixed donor sources.

INTRODUCTION: It is important to prepare 'hypoimmunogenic' or 'universal' human pluripotent stem cells (hPSCs) with gene-editing technology by knocking out or in immune-related genes, because only a few hypoimmunogenic or universal hPSC lines would be sufficient to store for their off-the-shelf use. However, these hypoimmunogenic or universal hPSCs prepared previously were all genetically edited, which makes laborious processes to check and evaluate no abnormal gene editing of hPSCs. METHODS: Universal human-induced pluripotent stem cells (hiPSCs) were generated without gene editing, which were reprogrammed from foetal stem cells (human amniotic fluid stem cells) with mixing 2-5 allogenic donors but not with single donor. We evaluated human leucocyte antigen (HLA)-expressing class Ia and class II of our hiPSCs and their differentiated cells into embryoid bodies, cardiomyocytes and mesenchymal stem cells. We further evaluated immunogenic response of transient universal hiPSCs with allogenic mononuclear cells from survival rate and cytokine production, which were generated by the cells due to immunogenic reactions. RESULTS: Our universal hiPSCs during passages 10-25 did not have immunogenic reaction from allogenic mononuclear cells even after differentiation into cardiomyocytes, embryoid bodies and mesenchymal stem cells. Furthermore, the cells including the differentiated cells did not express HLA class Ia and class II. Cardiomyocytes differentiated from transient universal hiPSCs at passage 21-22 survived and continued beating even after treatment with allogenic mononuclear cells.

Efficient differentiation of human pluripotent stem cells into cardiomyocytes on cell sorting thermoresponsive surface.

The current differentiation process of human pluripotent stem cells (hPSCs) into cardiomyocytes to enhance the purity of hPSC-derived cardiomyocytes requires some purification processes, which are laborious processes. We developed cell sorting plates, which are prepared from coating thermoresponsive poly(N-isopropylacrylamide) and extracellular matrix proteins. After hPSCs were induced into cardiomyocytes on the thermoresponsive surface coated with laminin-521 for 15 days, the temperature of the cell culture plates was decreased to 8-9 °C to detach the cells partially from the thermoresponsive surface. The detached cells exhibited a higher cardiomyocyte marker of cTnT than the remaining cells on the thermoresponsive surface as well as the cardiomyocytes after purification using conventional cell selection. The detached cells expressed several cardiomyocyte markers, such as α-actinin, MLC2a and NKX2.5. This study suggested that the purification of hPSC-derived cardiomyocytes using cell sorting plates with the thermoresponsive surface is a promising method for the purification of hPSC-derived cardiomyocytes without conventional laborious processes.

Generation of universal and hypoimmunogenic human pluripotent stem cells.

There is a need to store very large numbers of conventional human pluripotent stem cell (hPSC) lines for their off-the-shelf usage in stem cell therapy. Therefore, it is valuable to generate "universal" or "hypoimmunogenic" hPSCs with gene-editing technology by knocking out or in immune-related genes. A few universal or hypoimmunogenic hPSC lines should be enough to store for their off-the-shelf usage. Here, we overview and discuss how to prepare universal or hypoimmunogenic hPSCs and their disadvantages. ß2-Microglobulin-knockout hPSCs did not harbour human leukocyte antigen (HLA)-expressing class I cells but rather activated natural killer (NK) cells. To avoid NK cell and macrophage activities, homozygous hPSCs expressing a single allele of an HLA class I molecule, such as HLA-C, were developed. Major HLA class I molecules were knocked out, and PD-L1, HLA-G and CD47 were knocked in hPSCs using CRISPR/Cas9 gene editing. These cells escaped activation of not only T cells but also NK cells and macrophages, generating universal hPSCs.

Enrichment of cancer-initiating cells from colon cancer cells through porous polymeric membranes by a membrane filtration method.

Cancer-initiating cells (CICs) or cancer stem cells (CSCs) are primarily responsible for tumor initiation, growth, and metastasis and represent a few percent of the total tumor cell population. We designed a membrane filtration protocol to enrich CICs (CSCs) from the LoVo colon cancer cell line via nylon mesh filter membranes with 11 and 20 µm pore sizes and poly(lactide-co-glycolic acid)/silk screen (PLGA/silk screen) porous membranes (pore sizes of 20-30 µm). The colon cancer cell solution was filtered through the membranes to obtain a permeate solution. Subsequently, the cell culture medium was filtered through the membranes to collect the recovery solution where the cells attached to the membranes were rinsed off into the recovery solution. Then, the membranes were cultivated in the cultivation medium to collect the migrated cells from the membranes. The cells migrated from any membrane had higher expression of the CSC surface markers CD44 and CD133, had higher colony formation levels, and produced more carcinoembryonic antigen (CEA) than the colon cancer cells cultivated on conventional tissue culture plates (control). We established a method to enrich the CICs (CSCs) of colon cancer cells from migrated cells through porous polymeric membranes by the membrane filtration protocol developed in this study.

Culture and differentiation of purified human adipose-derived stem cells by membrane filtration via nylon mesh filters.

Human adipose-derived stem cells (hASCs) cultured for 5 passages were filtered through nylon (NY) mesh filter membranes coated with and without extracellular matrix proteins to obtain the permeation solution. Subsequently, the culture media were filtered via the membranes to obtain the recovery solution. Then, the membranes were cultured in cell culture medium to obtain the migrated cells from the membranes. The hASCs in the permeation solution, through any type of NY mesh filter membrane having 11 and 20 µm pore sizes, had lower osteogenic differentiation ability than conventional hASCs cultured on tissue culture polystyrene (TCP) dishes for passage 5, whereas the hASCs purified by the membrane migration method through NY mesh filter membranes coated with recombinant vitronectin, which have 11 and 20 µm pore sizes, showed a higher proliferation speed as well as higher osteogenic differentiation potential than the conventional hASCs cultured on TCP dishes for passage 5. The membrane filtration and migration methods would be useful for cell sorting for specific cells, such as hASCs with high proliferation and high osteogenic differentiation ability, which do not need antibody binding or genetic modification of the cells for the specific isolation of the cells.