Autologous antigen-presenting cells efficiently expand piggyBac transposon CAR-T cells with predominant memory phenotype.

The quality of chimeric antigen receptor (CAR)-T cell products, including the expression of memory and exhaustion markers, has been shown to influence their long-term functionality. The manufacturing process of CAR-T cells should be optimized to prevent early T cell exhaustion during expansion. Activation of T cells by monoclonal antibodies is a critical step for T cell expansion, which may sometimes induce excess stimulation and exhaustion of T cells. Given that piggyBac transposon (PB)-based gene transfer could circumvent the conventional pre-activation of T cells, we established a manufacturing method of PB-mediated HER2-specific CAR-T cells (PB-HER2-CAR-T cells) that maintains their memory phenotype without early T cell exhaustion. Through stimulation of CAR-transduced T cells with autologous peripheral blood mononuclear cell-derived feeder cells expressing both truncated HER2, CD80, and 4-1BBL proteins, we could effectively propagate memory-rich, PD-1-negative PB-HER2-CAR-T cells. PB-HER2-CAR-T cells demonstrated sustained antitumor efficacy in vitro and debulked the HER2-positive tumors in vivo. Mice treated with PB-HER2-CAR-T cells rejected the second tumor establishment owing to the in vivo expansion of PB-HER2-CAR-T cells. Our simple and effective manufacturing process using PB system and genetically modified donor-derived feeder cells is a promising strategy for the use of PB-CAR-T cell therapy.

Natural Killer T Cell-Targeted Immunotherapy Mediating Long-term Memory Responses and Strong Antitumor Activity.

Current tumor therapies, including immunotherapies, focus on passive eradication or at least reduction of the tumor mass. However, cancer patients quite often suffer from tumor relapse or metastasis after such treatments. To overcome these problems, we have developed a natural killer T (NKT) cell-targeted immunotherapy focusing on active engagement of the patient's immune system, but not directly targeting the tumor cells themselves. NKT cells express an invariant antigen receptor α chain encoded by Trav11 (Vα14)-Traj18 (Jα18) gene segments in mice and TRAV10 (Vα24)-TRAJ18 (Jα18) in humans and recognize glycolipid ligand in conjunction with a monomorphic CD1d molecule. The NKT cells play a pivotal role in the orchestration of antitumor immune responses by mediating adjuvant effects that activate various antitumor effector cells of both innate and adaptive immune systems and also aid in establishing a long-term memory response. Here, we established NKT cell-targeted therapy using a newly discovered NKT cell glycolipid ligand, RK, which has a stronger capacity to stimulate both human and mouse NKT cells compared to previous NKT cell ligand. Moreover, RK mediates strong adjuvant effects in activating various effector cell types and establishes long-term memory responses, resulting in the continuous attack on the tumor that confers long-lasting and potent antitumor effects. Since the NKT cell ligand presented by the monomorphic CD1d can be used for all humans irrespective of HLA types, and also because NKT cell-targeted therapy does not directly target tumor cells, this therapy can potentially be applied to all cancer patients and any tumor types.

Alternative pathway for the development of Vα14+ NKT cells directly from CD4-CD8- thymocytes that bypasses the CD4+CD8+ stage.

Although invariant Vα14+ natural killer T cells (NKT cells) are thought to be generated from CD4+CD8+ double-positive (DP) thymocytes, the developmental origin of CD4-CD8- double-negative (DN) NKT cells still remains unresolved. Here we provide definitive genetic evidence obtained, through studies of mice with DP-stage-specific ablation of expression of the gene encoding the recombinase component RAG-2 (Rag2) and by a fate-mapping approach, that supports the proposal of the existence of an alternative developmental pathway through which a fraction of DN NKT cells with strong T-helper-type-1 (TH1)-biased and cytotoxic characteristics develop from late DN-stage thymocytes, bypassing the DP stage. These findings provide new insight into understanding of the development of NKT cells and propose a role for timing of expression of the invariant T cell antigen receptor in determining the functional properties of NKT cells.

Generation of Novel Traj18-Deficient Mice Lacking Vα14 Natural Killer T Cells with an Undisturbed T Cell Receptor α-Chain Repertoire.

Invariant Vα14 natural killer T (NKT) cells, characterized by the expression of a single invariant T cell receptor (TCR) α chain encoded by rearranged Trav11 (Vα14)-Traj18 (Jα18) gene segments in mice, and TRAV10 (Vα24)-TRAJ18 (Jα18) in humans, mediate adjuvant effects to activate various effector cell types in both innate and adaptive immune systems that facilitates the potent antitumor effects. It was recently reported that the Jα18-deficient mouse described by our group in 1997 harbors perturbed TCRα repertoire, which raised concerns regarding the validity of some of the experimental conclusions that have been made using this mouse line. To resolve this concern, we generated a novel Traj18-deficient mouse line by specifically targeting the Traj18 gene segment using Cre-Lox approach. Here we showed the newly generated Traj18-deficient mouse has, apart from the absence of Traj18, an undisturbed TCRα chain repertoire by using next generation sequencing and by detecting normal generation of Vα19Jα33 expressing mucosal associated invariant T cells, whose development was abrogated in the originally described Jα18-KO mice. We also demonstrated here the definitive requirement for NKT cells in the protection against tumors and their potent adjuvant effects on antigen-specific CD8 T cells.

Synthesis of RCAI-172 (C6 epimer of RCAI-147) and its biological activity.

RCAI-147 is one of the hydroxylated analogues of KRN7000 which is known as a ligand for the activation of CD1d mediated invariant natural killer T cells (iNKT cells) and releases both T helper 1 (Th1) cytokines such as IFN-γ and T helper 2 (Th2) cytokines such as IL-4. KRN7000 has been anticipated as an antitumor drug or an adjuvant for viral infection such as influenza, because of its strong secretion of IFN-γ. In an interesting twist, it has been obvious in our previous paper that RCAI-147 induces much more Th2 cytokines (IL-4) than Th1 cytokines (IFN-γ) from iNKT cells compared to KRN7000, and shows fairly good result in the experimental autoimmune encephalomyelitis (EAE) test. Therefore, synthesis of RCAI-172 (C6-OH epimer of RCAI-147) was attempted to examine the biological activity. As a result, RCAI-172 was synthesized and its biological activity biased to Th2 response largely compared to that of KRN7000. However, this level decreased to approximately 61% compared to that of RCAI-147. And the clinical score of RCAI-172 for EAE suppression was disappointing. There exist seven chiral centers in the aglycon part of RCAI-172, and even though the change of configuration is just one position (C6-OH), the effect on both Th1/Th2 response and EAE test is fairly large.

RCAI-61 and related 6'-modified analogs of KRN7000: their synthesis and bioactivity for mouse lymphocytes to produce interferon-γ in vivo.

We synthesized ten new analogs of 6'-modified KRN7000 (A): RCAI-58, 61, 64, 83, 85-87, 113, 119, and 125. They could be synthesized by α-selective galactosylation of ceramide 9 with the 6-modified D-galactopyranosyl fluorides (8a-8f) or L-arabinopyranosyl fluoride (17), or by etherification of the known alcohol 19. Bioassay of the ten analogs demonstrated that RCAI-61 (1, 6'-O-methylated analog of A) was the most potent immunostimulant among them, and could induce the production of a large amount of IFN-γ even at a low concentration in mice in vivo.

Synthesis and biological activity of hydroxylated analogues of KRN7000 (α-galactosylceramide).

KRN7000 is one of the α-galactosylceramides, which has a 2-hexacosanoylamino-3,4-dihydroxyoctadecyl group. This compound, known as a ligand for the activation of CD1d mediated invariant natural killer T cells (iNKT cells) which release both T helper 1 (Th1) cytokines such as IFNγ and Th2 cytokines such as IL-4, has been anticipated as an antitumor drug, because of its strong secretion of IFNγ. This time, we focused on the hydroxylated analogues of KRN7000 which could be thought of as increasing hydrophilicity and showing bias to Th2 cytokine (IL-4) secretion. Therefore, they may become the drugs for autoimmune diseases for the following reasons: (i) compound OCH, one of the α-galactosylceramide analogues with a shorter sphingosine chain than KRN7000, increases hydrophilicity relative to KRN7000; and (ii) OCH is known to induce much more Th2 cytokines (IL-4) than Th1 cytokines from iNKT cells compared to KRN7000. Naturally, OCH has become one of the candidate drugs for autoimmune diseases. The more hydroxylated derivatives of KRN7000 are anticipated to induce Th2 bias. Therefore, eight analogues with 1-4 excess hydroxyl groups on the lipid chain of KRN7000 were synthesized to examine if they behave in the same way as OCH. As a result, three out of eight compounds biased largely to IL-4 secretion, and their effectiveness for experimental autoimmune encephalomyelitis (EAE) was examined. It was recognized that two compounds (†)RCAI-147/-160 showed good suppression of EAE symptoms.

Synthesis and biological activity of ester and ether analogues of alpha-galactosylceramide (KRN7000).

Alpha-Galactosylceramide (alphaGalCer, KRN7000) has been identified as a modulator of immunological processes through its capacity to bind iNKT cells mediated by CD1d molecules. Some analogues in while the amide group in alphaGalCer is replaced with ester or ether groups were synthesized from d-arabinitol or l-ribose to evaluate their ability to activate iNKT cells. Ester analogues 30a, 31a, and 61 showed activity for IFNgamma and IL-4 production of iNKT cells, while ether (31b) and 4-methoxy ester (76) analogues of alpha-galactosylceramide were not active for iNKT cells.

Induction of Th1-biased cytokine production by alpha-carba-GalCer, a neoglycolipid ligand for NKT cells.

NKT cells are characterized by their production of both T(h)1 and T(h)2 cytokines immediately after stimulation with alpha-galactosylceramide (alpha-GalCer), which is composed of alpha-galactopyranose linked to ceramide (itself composed of sphingosine and fatty-acyl chains); the chain length of the ceramide varies and this affects the ability of alpha-GalCer to stimulate cytokine production. However, the contribution of its galactopyranose sugar moiety remains unclear. We synthesized alpha-carba-GalCer, which has an alpha-linked carba-galactosyl moiety; here, the 5a'-oxygen atom of the D-galactopyranose ring of alpha-GalCer is replaced by a methylene group. The alpha-carba-GalCer was more stable and showed higher affinity to the NKT receptor. It thus enhanced and prolonged production of IL-12 and IFN-gamma compared with alpha-GalCer, resulting in augmented NKT cell-mediated adjuvant effects in vivo. The alpha-carba-GalCer, which has an ether linkage, was more resistant to degradation by liver microsomes than was alpha-GalCer, which has an acetal bond. Modulation of the sugar moiety in glycolipids might therefore provide optimal therapeutic reagents for protective immune responses against tumor or pathogens.

Numerical measurement of viable and nonviable adipocytes and other cellular components in aspirated fat tissue.

BACKGROUND: A reliable method with which to assay viability and number of adipocytes and other cellular components in adipose tissue remains to be established. METHODS: The authors assessed cell viability and number obtained from 1 g of suctioned adipose tissue and respective layers (the top, middle, and bottom layers) before and after digestion and centrifugation, using cell staining with Hoechst 33342 and propidium iodide and the 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenyl-amino)carbonyl]-2H-tetrazoliumhydroxide (XTT) and glycerol-3-phosphate dehydrogenase assays (n = 10). The correlation between the number of prepared cells (adipocytes, adipose stromal cells, and white blood cells) and the resulting values from the XTT and glycerol-3-phosphate dehydrogenase assays was also examined (n = 5). The cell composition of the stromal vascular fraction isolated from the same adipose tissue was determined by multicolor flow cytometry (n = 5). RESULTS: Hoechst 33342 and propidium iodide staining allowed distinguishing of viable adipocytes from lipid droplets, dead adipocytes, and cells other than adipocytes. The authors obtained 6.9 x 10 nonruptured adipocytes from 1 g of suctioned adipose tissue; 30 percent of the original adipocytes appeared to have been ruptured. Both the XTT and glycerol-3-phosphate dehydrogenase assays provided good correlations between the number of viable adipocytes and resulting values, but only the glycerol-3-phosphate dehydrogenase assay was strictly specific for adipocytes. The ratio of adipose stromal cells to adipocytes was found to be much larger than previously described. CONCLUSION: Single use or a combination of the viability assays used in this study can appropriately determine the number of adipocytes and other cells, although it remains difficult to assess original cells directly without tissue dissociation.

Differential effects of three preparations of human serum on expansion of various types of human cells.

BACKGROUND: To avoid potential risks of animal-derived products such as viral transmission and immunologic reactions, usefulness of human-derived products in manipulation of cells for cell-based therapies has been investigated but has not yet been completely clarified. METHODS: Three types of human sera-serum from whole blood, serum from platelet-rich plasma, and serum from platelet-poor plasma-were prepared from blood samples obtained from the same four volunteers. The authors investigated the biochemical profiles of the three serum preparations as well as their potential as culture additives using three types of human cells: dermal fibroblasts, adipose-derived stem/stromal cells, and umbilical vein endothelial cells. RESULTS: Platelet counts differed among serum from whole blood (100 percent), platelet-rich plasma (75.1 percent), and platelet-poor plasma (12.6 percent), resulting in differential concentrations of platelet-derived growth factor and epidermal growth factor, although other biochemical values such as total protein and albumin were similar. Serum from whole blood and platelet-rich plasma highly enhanced proliferation of dermal fibroblasts compared with the effects of serum from platelet-poor plasma, but no differences in proliferative efficacy were observed in cultures of adipose-derived stem/stromal cells and vascular endothelial cells. CONCLUSIONS: Serum from platelet-rich plasma, which is less invasive to prepare than serum from whole blood, was superior to serum from platelet-poor plasma as a substitute for animal-derived serum in culture expansion of dermal fibroblasts. Although autologous or human-derived serum preparations may be of great use in cell-based therapies, this usefulness strongly depends on the target cell species and the purpose of the cell culture.

Influences of centrifugation on cells and tissues in liposuction aspirates: optimized centrifugation for lipotransfer and cell isolation.

BACKGROUND: Although injective autologous fat transplantation is one of the most attractive options for soft-tissue augmentation, problems such as unpredictability and fibrosis resulting from fat necrosis limit its universal acceptance. Centrifugation is one of most common methods for overcoming these difficulties. This study was performed to investigate quantitatively the effects of centrifugation on liposuction aspirates to optimize centrifugal conditions for fat transplantation and isolation of adipose-derived stem cells. METHODS: Liposuction aspirates, obtained from eight healthy female donors, were either not centrifuged or centrifuged at 400, 700, 1200, 3000, or 4200 g for 3 minutes. The volumes of the oil, adipose, and fluid portions and numbers of blood cells and adipose-derived cells in each portion were examined. The processed adipose tissues (1 ml) were injected into athymic mice, and grafts were harvested and weighed at 4 weeks. Morphologic alterations were observed using light and scanning electron microscopy. RESULTS: Centrifugation concentrated adipose tissues and adipose-derived stem cells in the adipose portion and partly removed red blood cells from the adipose portion. Centrifugation at more than 3000 g significantly damaged adipose-derived stem cells. Centrifugation enhanced graft take per 1 ml centrifuged adipose but reduced calculated graft take per 1 ml adipose before centrifugation. CONCLUSIONS: Excessive centrifugation can destroy adipocytes and adipose-derived stem cells, but appropriate centrifugation concentrates them, resulting in enhanced graft take. The authors tentatively recommend 1200 g as an optimized centrifugal force for obtaining good short- and long-term results in adipose transplantation.

Preserved proliferative capacity and multipotency of human adipose-derived stem cells after long-term cryopreservation.

BACKGROUND: Human adipose-derived stem (stromal) cells are promising as a regenerative therapy tool for defective tissues of mesenchymal lineage, including fat, bone, and cartilage, and blood vessels. In potential future clinical applications, adipose-derived stem cell cryopreservation could be an indispensable fundamental technology, as has occurred in other fields involving cell-based therapies using hematopoietic stem cells and umbilical cord blood cells. METHODS: The authors examined the proliferative capacity and multipotency of human adipose-derived stem cells isolated from lipoaspirates of 18 patients in total before and after a 6-month cryopreservation following their defined protocol. Proliferative capacity was quantified by measuring doubling time in cell culture, and multipotency was examined with differentiation assays for chondrogenic, osteogenic, and adipogenic lineages. In addition, expression profiles of cell surface markers were determined by flow cytometry and compared between fresh and cryopreserved adipose-derived stem cells. RESULTS: Cryopreserved adipose-derived stem cells fully retained the potential for differentiation into adipocytes, osteoblasts, and chondrocytes and for proliferative capacity. Flow cytometric analyses revealed that surface marker expression profiles remained constant before and after storage. CONCLUSIONS: Adipose-derived stem cells can be cryopreserved at least for up to 6 months under the present protocol without any loss of proliferative or differentiation potential. These results ensure the availability of autologous banked adipose-derived stem cells for clinical applications in the future.

Influences of preservation at various temperatures on liposuction aspirates.

BACKGROUND: Aspirated fat is not only a filler material but also an abundant source of adipose-derived stem cells. The aim of this study was to assess degeneration of aspirated fat during preservation and optimize the preservation method for lipoaspirates. METHODS: Aspirated fat was preserved at room temperature for 1, 2, 4, and 24 hours (n = 10 each); at 4 degrees C for 1, 2, and 3 days (n = 14 each); or at -80 degrees C for 1 month (n = 3). Morphologic changes were assessed with scanning electron microscopy. Adipose-derived stem cell yield was measured after 1 week of culture. For aspirated fat preserved at room temperature, damaged adipocytes were assessed by measuring the oil volume ratio after centrifugation (n = 6) and glycerol-3-phosphate-dehydrogenase activity in washing solution (n = 4). Cell surface marker expression was examined by flow cytometry (n = 3). RESULTS: Although the scanning electron microscopic assay indicated no remarkable anatomical changes based on preservation methods, oil volume significantly increased in fat preserved at room temperature for 4 hours. Adipose-derived stem cell yield was significantly reduced by preservation at room temperature for 24 hours and by preservation at 4 degrees C for 2 or 3 days. Flow cytometric analysis suggested that the biological properties of adipose-derived stem cells did not significantly change at 4 degrees C up to 3 days. The cells were isolated from cryopreserved fat, but the yield was much less than that from fresh aspirated fat. CONCLUSIONS: Aspirated fat should be transplanted as quickly as possible if it is preserved at room temperature. For adipose-derived stem cell isolation, aspirated fat can be stored or transported overnight if it is preserved at 4 degrees C without adipose-derived stem cell yield loss or changes in biological properties.

Neurospheres from human adipose tissue transplanted into cultured mouse embryos can contribute to craniofacial morphogenesis: a preliminary report.

Adipose-derived stromal cells (ASCs) are one of the most promising stem cell populations that differentiate into the mesodermal as well as neural lineages in vitro. In this study, we examined the neural differentiating potential of human ASCs by a neurosphere culture method. Neurospheres derived from human ASCs expressed Nestin and Musashi-1 genes, which are marker genes for neural stem cells. When these cells were labeled with green fluorescent protein gene transfection by Sendai virus vector and transplanted into the head region of mouse embryos using a whole embryo culture system, these cells were incorporated into the craniofacial development. Some transplanted cells appeared to migrate along the second branchial arches, implicating some similarity to the cranial neural crest cells. Although preliminary, our results support an idea that ASC-derived neurospheres have properties of neural progenitors in vitro and in vivo.

Cell-assisted lipotransfer: supportive use of human adipose-derived cells for soft tissue augmentation with lipoinjection.

Injective transfer of autologous aspirated fat is a popular option for soft tissue augmentation, but several issues require attention, including unpredictability and a low survival rate due to partial necrosis. In this study, histologic features and yield of adipose-derived stromal (stem) cells (ASCs) were compared between human aspirated fat and excised whole fat. Aspirated fat contained fewer large vascular structures, and ASC yield was lower in aspirated fat. Aspirated fat was transplanted subcutaneously into severe combined immunodeficiency mice with (cell-assisted lipotransfer; CAL) or without (non-CAL) vascular stromal fractions containing ASCs isolated from adipose tissue. The CAL fat survived better (35% larger on average) than non-CAL fat, and microvasculature was detected more prominently in CAL fat, especially in the outer layers. DiI-labeled vascular stromal fraction cells were found between adipocytes and in the connective tissue in CAL fat, and some of these cells were immunopositive for von Willebrand factor, suggesting differentiation into vascular endothelial cells. Another experiment that used vascular stromal fractions taken from green fluorescent protein rats also suggested that ASCs differentiated into vascular endothelial cells and contributed to neoangiogenesis in the acute phase of transplantation. These findings may partly explain why transplanted aspirated fat does not survive well and suggest clinical potential of the CAL method for soft tissue augmentation.

Teratogenic and anti-metamorphic effects of bisphenol A on embryonic and larval Xenopus laevis.

Effects of bisphenol A (BPA) on embryonic and larval development were investigated. In Xenopus laevis blastulae treated with 2.5-3.0 x 10(-5) M BPA or with 10(-5) M 17beta estradiol (E2), malformation of the head region, scoliosis (curved vertebrate), and suppression of organogenesis were observed. In addition, 10(-5)-10(-4) M BPA blocked tri-iodothyronine (T3)-inducible resorption of the tail segments from premetamorphic (stage 52-54) larvae in vitro. When stage 52 tadpoles were immersed in 1.0-2.5 x 10(-5) M BPA, deceleration of both spontaneous and thyroxin (T4)-induced metamorphic changes occurred. Furthermore, BPA suppressed thyroid hormone receptor (TR) beta gene expression both in vivo and in vitro. Thus, we concluded that BPA at the concentrations examined affects both embryonic development and larval metamorphosis.