Introduction to a new cell transplantation platform via recombinant peptide petaloid pieces and its application to islet transplantation with mesenchymal stem cells

A Recombinant Peptide Device Combined with Adipose Tissue-Derived Stem Cells Enhances Subcutaneous Islet Engraftment

Subcutaneous space has been considered an attractive site for islet graft transplantation; however, the oxygen tension and vascularization are insufficient for islet graft survival. We investigated whether subcutaneous pre-implantation of a recombinant peptide (RCP) device with adipose tissue-derived stem cells (ADSCs) enhanced subcutaneous islet engraftment. RCP devices with/without syngeneic ADSCs were pre-implanted into the subcutaneous space of C57BL/6 mice. Syngeneic islets (300 or 120 islet equivalents (IEQs)) were transplanted into the pre-treated space after diabetes induction using streptozotocin. The cure rates of groups in which RCP devices were implanted four weeks before transplantation were significantly better than the intraportal transplantation group when 300 IEQs of islets were transplanted (p < 0.01). The blood glucose changes in the RCP+ADSCs-4w group was significantly ameliorated in comparison to the RCP-4w group when 120 IEQs of islets were transplanted (p < 0.01). Immunohistochemical analyses showed the collagen III expression in the islet capsule of the RCP+ADSCs-4w group was significantly enhanced in comparison to the RCP-4w and RCP+ADSCs-d10 groups (p < 0.01, p < 0.01). In addition, the number of von Willebrand factor-positive vessels within islets in the RCP+ADSCs-4w group was significantly higher than the RCP-4w group. These results suggest that using ADSCs in combination with an RCP device could enhance the restoration of the extracellular matrices, induce more efficient prevascularization within islets, and improve the graft function.

Collagen type I-based recombinant peptide promotes bone regeneration in rat critical-size calvarial defects by enhancing osteoclast activity at late stages of healing

Introduction

We recently demonstrated the bone-forming potential of medium-cross-linked recombinant collagen peptide (mRCP) in animal models of bone defects. However, these studies were limited to a 4-week observation period; therefore, in the present study, we aimed to further evaluate mRCP as a suitable bone graft material for the alveolar cleft by analyzing its bone-forming potential, osteogenic-inducing ability, and biodegradation over an extended period of 12 weeks, using a rat critical-size calvarial defect model.

Methods

Using Sprague-Dawley rats, we created critical-size calvarial defects through a surgical procedure. The defects were then filled with 3 mg of mRCP (mRCP group) or 18 mg of Cytrans® (CA) granules, which has a carbonate apatite-based composition resembling natural bone, was used as a reference material (CA group). For negative control, the defects were left untreated. Bone volume, total bone volume (bone volume including CA granules), and bone mineral density (BMD) in the defect were assessed using micro-computed tomography (μ-CT) at 0, 4, 8, and 12 weeks after implantation. Using histomorphometric analyses of hematoxylin and eosin (H&E)-stained sections, we measured the amount of newly formed bone and total newly formed bone (new bone including CA granules) in the entire defect site, as well as the amount of newly formed bone in the central side, two peripheral sides (left and right), periosteal (top) side, and dura mater (bottom) side. In addition, we measured the amount of residual bone graft material in the defect. Osteoclasts and osteoblasts in the newly formed bone were detected using tartrate-resistant acid phosphatase (TRAP) and alkaline phosphatase (ALP) staining, respectively.

Results

Bone volume in the mRCP group increased over time and was significantly larger at 8 and 12 weeks after surgery than at 4 weeks. The bone volume in the mRCP group was greater than that of the CA and control groups at 4, 8, and 12 weeks after implantation, and while the total bone volume was greater in the CA group after 4 and 8 weeks, the mRCP group had comparable levels of total bone volume to that of the CA group at 12 weeks after implantation. The BMD of the mRCP group reached similar levels to native calvaria bone at the same time point. H&E-stained sections revealed a larger amount of newly formed bone 12 weeks after implantation in the mRCP group compared to that of the CA and control groups. The total newly formed bone at 12 weeks after implantation was on par with that in the CA group. Furthermore, at the defect site, the area of newly formed bone was larger on the peripheral and dura mater sides. Notably, the number of osteoclasts in the mRCP group was higher than in the CA and control groups and peaked 8 weeks after implantation, which coincided with the timing of the greatest resorption of mRCP. Although the ALP-positive area was greater in the mRCP group compared to other groups, we did not detect any significant changes in the number of osteoblasts over time.

Conclusion

This study demonstrated the bone-forming potential of mRCP over an extended period of 12 weeks, suggesting that mRCP sufficiently resists resorption to promote bone formation through induction of osteoclast activation in the late stages of the healing period.

Periodontal tissue regeneration by recombinant human collagen peptide granules applied with β-tricalcium phosphate fine particles

OBJECTIVES

Recombinant human collagen peptide (RCP) is a recombinantly created xeno-free biomaterial enriched in arginine-glycine-aspartic acid sequences with good processability whose use for regenerative medicine applications is under investigation. The biocompatibility and osteogenic ability of RCP granules combined with β-tricalcium phosphate (TCP) submicron particles (β-TCP/RCP) were recently demonstrated. In the present study, β-TCP/RCP was implanted into experimental periodontal tissue defects created in beagles to investigate its regenerative effects.

METHODS

An RCP solution was lyophilized, granulated, and thermally cross-linked into particles approximately 1 mm in diameter. β-TCP dispersion (1 wt%; 500 μL) was added to 100 mg of RCP granules to form β-TCP/RCP. A three-walled intrabony defect (5 mm × 3 mm × 4 mm) was created on the mesial side of the mandibular first molar and filled with β-TCP/RCP.

RESULTS

A micro-computed tomography image analysis performed at 8 weeks postoperative showed a significantly greater amount of new bone after β-TCP/RCP grafting (2.2-fold, P < 0.05) than after no grafting. Histological findings showed that the transplanted β-TCP/RCP induced active bone-like tissue formation including tartaric acid-resistant acid phosphatase- and OCN-positive cells as well as bioabsorbability. Ankylosis did not occur, and periostin-positive periodontal ligament-like tissue formation was observed. Histological measurements performed at 8 weeks postoperative revealed that β-TCP/RCP implantation formed 1.7-fold more bone-like tissue and 2.1-fold more periodontal ligament-like tissue than the control condition and significantly suppressed gingival recession and epithelial downgrowth (P < 0.05).

CONCLUSIONS

β-TCP/RCP implantation promoted bone-like and periodontal ligament-like tissue formation, suggesting its efficacy as a periodontal tissue regenerative material.

Appropriate pore size for bone formation potential of porous collagen type I-based recombinant peptide

Introduction

In this study, we developed porous medium cross-linked recombinant collagen peptide (mRCP) with two different ranges of interconnected pore sizes, Small-mRCP (S-mRCP) with a range of 100–300 μm and Large-mRCP (L-mRCP) with a range of 200–500 μm, to compare the effect of pore size on bone regeneration in a calvarial bone defect.

Methods

Calvarial bone defects were created in Sprague–Dawley rats through a surgical procedure. The rats were divided into 2 groups: S-mRCP implanted group and L-mRCP implanted group. The newly formed bone volume and bone mineral density (BMD) was evaluated by micro-computed tomography (micro-CT) immediately after implantation and at 1, 2, 3, and 4 weeks after implantation. In addition, histological analyses were carried out with hematoxylin and eosin (H&E) staining at 4 weeks after implantation to measure the newly formed bone area between each group in the entire defect, as well as the central side, the two peripheral sides (right and left), the periosteal (top) side and the dura matter (bottom) side of the defect.

Results

Micro-CT analysis showed no significant differences in the amount of bone volume between the S-mRCP and L-mRCP implanted groups at 1, 2, 3 and 4 weeks after implantation. BMD was equivalent to that of the adjacent native calvaria bone at 4 weeks after implantation. H&E images showed that the newly formed bone area in the entire defect was significantly larger in the S-mRCP implanted group than in the L-mRCP implanted group. Furthermore, the amount of newly formed bone area in all sides of the defect was significantly more in the S-mRCP implanted group than in the L-mRCP implanted group.

Conclusion

These results indicate that the smaller pore size range of 100–300 μm is appropriate for mRCP in bone regeneration.

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This study confirmed the regenerative potential of mRCP as novel bone substitute.

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mRCP with 2 different interconnected pores sizes have been developed.

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The smaller pore size range of 100–300 μm was optimal for calvarial bone regeneration.

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The slower absorption rate of smaller pore size mRCP influenced its effectiveness.

Intracerebral Transplantation of Mesenchymal Stromal Cell Compounded with Recombinant Peptide Scaffold against Chronic Intracerebral Hemorrhage Model

Background

Due to the lack of effective therapies, stem cell transplantation is an anticipated treatment for chronic intracerebral hemorrhage (ICH), and higher cell survival and engraftment are considered to be the key for recovery. Mesenchymal stromal cells (MSCs) compounded with recombinant human collagen type I scaffolds (CellSaics) have a higher potential for cell survival and engraftment compared with solo-MSCs, and we investigated the validity of intracerebral transplantation of CellSaic in a chronic ICH model.

Methods

Rat CellSaics (rCellSaics) were produced by rat bone marrow-derived MSC (rBMSCs). The secretion potential of neurotrophic factors and the cell proliferation rate were compared under oxygen-glucose deprivation (OGD) conditions. rCellSaics, rBMSCs, or saline were transplanted into the hollow cavity of a rat chronic ICH model. Functional and histological analyses were evaluated, and single-photon emission computed tomography for benzodiazepine receptors was performed to monitor sequential changes in neuronal integrity. Furthermore, human CellSaics (hCellSaics) were transplanted into a chronic ICH model in immunodeficient rats. Antibodies neutralizing brain-derived neurotrophic factor (BDNF) were used to elucidate its mode of action.

Results

rCellSaics demonstrated a higher secretion potential of trophic factors and showed better cell proliferation in the OGD condition. Animals receiving rCellSaics displayed better neurological recovery, higher intracerebral BDNF, and better cell engraftment; they also showed a tendency for less brain atrophy and higher benzodiazepine receptor preservation. hCellSaics also promoted significant functional recovery, which was reversed by BDNF neutralization.

Conclusion

Intracerebral transplantation of CellSaics enabled neurological recovery in a chronic ICH model and may be a good option for clinical application.

Newly Generated 3D Schwann-Like Cell Spheroids From Human Adipose-Derived Stem Cells Using a Modified Protocol

Peripheral nerve injury (PNI) is a relatively frequent type of trauma that results in the suffering of many patients worldwide every year. Schwann cells (SCs) are expected to be applied in cell therapy because of their ability to promote peripheral nerve regeneration. However, the lack of clinically renewable sources of SCs hinders the application of SC-based therapies. Adipose-derived stem cells (ADSCs) have generated great interest in recent years because of their multipotency and ease of harvest, and they have already been verified to differentiate into Schwann-like cells (SLCs) in vitro. However, the efficiency of differentiation and the functions of SLCs remain unsatisfactory. We newly generated three-dimensional (3D) SLC spheroids from ADSCs using a modified protocol with human recombinant peptide (RCP) petaloid μ-piece. Morphological analysis, gene expression analysis by qRT-PCR, ELISA measurement of the secretion capabilities of neurotrophic factors, and neurite formation assay were performed to evaluate the functions of these 3D SLCs in vitro. Motor function recovery was measured in a sciatic nerve injury mouse model to analyze the nerve regeneration-promoting effect of 3D SLCs in vivo. The differentiation efficiency and the secretion of neurotrophic factors were enhanced in 3D SLCs compared with conventional SLCs. 3D SLCs could more effectively promote neurite growth and longer neurite extension in a neuron-like SH-SY5Y model. Additionally, 3D SLCs had a better therapeutic effect on nerve regeneration after transplantation into the sciatic nerve injury mouse model. These findings demonstrated that the potential of ADSC-derived SLCs to promote nerve regeneration could be significantly increased using our modified differentiation protocol and by assembling cells into a 3D sphere conformation. Therefore, these cells have great potential and can be used in the clinical treatment of PNI.

Genetically Modified Cell Transplantation Through Macroencapsulated Spheroids with Scaffolds to Treat Fabry Disease

Cell transplantation is expected to be another strategy to treat lysosomal diseases, having several advantages compared to enzyme replacement therapy, such as continuous enzyme secretion and one-time treatment to cure diseases. However, cell transplantation for lysosomal diseases holds issues to be resolved for the clinical field. In this study, we developed a new ex vivo gene therapy platform using a transplant pack, which consists of a porous membrane made of ethylene-vinyl alcohol in the pack-type and spheroids with scaffolds. These membranes have countless pores of less than 0.1 µm² capable of secreting proteins, including alpha-galactosidase enzyme, and segregating the contents from the host immune system. When the packs were subcutaneously transplanted into the backs of green fluorescent protein (GFP) mice, no GFP-positive cells migrated to the transplanted pack in either autogenic or allogenic mice. The transplanted cells in the pack survived for 28 days after transplantation. When cells overexpressing alpha-galactosidase were used as donor cells for the packs and implanted into Fabry disease model mice, the accumulation of the alpha-galactosidase enzyme was also observed in the livers. In this study, we reported a new ex vivo therapeutic strategy combining macroencapsulation and cellular spheroids with scaffolds. This pack, macroencapsulated spheroids with scaffolds, can also be applied to other types of lysosomal diseases by modifying genes of interest.

A Review of the Effects of Collagen Treatment in Clinical Studies

Collagen, an abundant extracellular matrix protein, has been found to have a lot of pharmaceuticals, medicine, food, and cosmetics applications. Increased knowledge of collagen sources, extraction techniques, structure, and properties in the last decades has helped develop more collagen-based products and tissue engineering biomaterials. Collagen products have been playing an important role in benefiting the health of the human body, especially for aging people. In this paper, the effects of collagen treatment in different clinical studies including skin regeneration, bone defects, sarcopenia, wound healing, dental therapy, gastroesophageal reflux, osteoarthritis, and rheumatoid arthritis have been reviewed. The collagen treatments were significant in these clinical studies. In addition, the associations between these diseases were discussed. The comorbidity of these diseases might be closely related to collagen deficiency, and collagen treatment might be a good choice when a patient has more than one of these diseases, including the coronavirus disease 2019 (COVID-19). It concludes that collagen-based medication is useful in treating comorbid diseases and preventing complications.

Comparison of Osteogenic Potentials of Dental Pulp and Bone Marrow Mesenchymal Stem Cells Using the New Cell Transplantation Platform, CellSaic, in a Rat Congenital Cleft-Jaw Model

Scaffolds stimulate cell proliferation and differentiation and play major roles in providing growth and nutrition factors in the repair of bone defects. We used the recombinant peptide Cellnest™ to prepare the three-dimensional stem cell complex, CellSaic, and evaluated whether CellSaic containing rat dental pulp stem cells (rDPSCs) was better than that containing rat bone marrow stem cells (rBMSCs). rDPSC-CellSaic or rBMSC-CellSaic, cultured with or without osteogenic induction medium, formed the experimental and control groups, respectively. Osteoblast differentiation was evaluated in vitro and transplanted into a rat model with a congenital jaw fracture. Specimens were collected and evaluated by microradiology and histological analysis. In the experimental group, the amount of calcium deposits, expression levels of bone-related genes (RUNX2, ALP, BSP, and COL1), and volume of mineralized tissue, were significantly higher than those in the control group (p < 0.05). Both differentiated and undifferentiated rDPSC-CellSaic and only the differentiated rBMSC-CellSaic could induce the formation of new bone tissue. Overall, rBMSC-CellSaic and rDPSC-CellSaic made with Cellnest™ as a scaffold, provide excellent support for promoting bone regeneration in rat mandibular congenital defects. Additionally, rDPSC-CellSaic seems a better source for craniofacial bone defect repair than rBMSC-CellSaic, suggesting the possibility of using DPSCs in bone tissue regenerative therapy.

Effective three-dimensional culture of hepatocyte-like cells generated from human adipose-derived mesenchymal stem cells

BACKGROUND

The aim of this study was to clarify the effectiveness of a new three-dimensional (3D) culture system for hepatocyte-like cells (HLCs) generated from human adipose-derived mesenchymal stem cells (ADSCs).

METHODS

Human ADSCs (2 × 10⁴ ) with or without 0.1 mg/mL human recombinant peptide μ-piece per well were seeded in a 96-well U-bottom plate and then our three-step differentiation protocol was applied for 21 days. At each step, cell morphology and gene expression were investigated. Mature hepatocyte functions were evaluated after HLC differentiation. These parameters were compared between 2D- and 3D-cultured HLCs, and, DNA microarray analysis was also performed. Finally, HLCs were transplanted in to CCl₄ induced acute liver failure model mice.

RESULTS

Two-dimensional-cultured HLCs at day 21 did not have a spindle shape and had formed spheroids after day 6, which gradually increased in size for 3D-cultured HLCs. Definitive endoderm, hepatoblast, and hepatocyte genes showed significantly higher expression in the 3D culture group. Three-dimensional-cultured HLCs also had higher albumin expression, CYP3A4 activity, urea synthesis, and ammonium metabolism, and much higher expression of ion transporter, blood coagulation, and cell communication genes. HLC transplantation improved serum liver function, especially in T-Bil levels, and engrafted into immunodeficient mice with HLA class I positive staining.

CONCLUSION

Our new 3D culture protocol is effective to improve hepatocyte functions. Our HLCs might be promising for clinical cell transplantation to treat metabolic disease.

Cell Transplantation Combined with Recombinant Collagen Peptides for the Treatment of Fabry Disease

Fabry disease is caused by a decrease in or loss of the activity of alpha-galactosidase, which causes its substrates globotriaosylceramide (Gb3) and globotriaosylsphingosine (lyso-Gb3) to accumulate in cells throughout the body. This accumulation results in progressive kidney injury due to glomerulosclerosis and in heart failure due to hypertrophy. Enzyme replacement therapy (ERT) has been used as the standard therapy for Fabry disease, but it causes a significant financial burden, and regular administration is inconvenient for patients. Because of the short half-life of alpha-galactosidase in vivo, therapeutic methods that can supplement or replace ERT are expected to involve continuous release of alpha-galactosidase, even at low doses. Cell transplantation therapy is one of these methods; however, its use has been hindered by the short-term survival of transplanted cells. CellSaic technology, which utilizes cell spheroids that form after cells are seeded simultaneously with a recombinant collagen peptide scaffold called a μ-piece, has been used to improve cell survival upon implantation. In this study, syngeneic murine embryonic fibroblasts were used to generate CellSaic that were transplanted into Fabry mice. These spheroids survived for 28 days in the renal subcapsular space with forming blood vessels. These results indicate CellSaic technology could be a platform to promote cellular graft survival and may facilitate the development of cell transplantation methods for lysosomal diseases.

The Fragility of Cryopreserved Insulin-producing Cells Differentiated from Adipose-tissue-derived Stem Cells

The aim of our study is to determine whether insulin-producing cells (IPCs) differentiated from adipose-tissue-derived stem cells (ADSCs) can be cryopreserved. Human ADSCs were differentiated into IPCs using our two-step protocol encompassing a three-dimensional culture and xenoantigen-free method. Thereafter, IPCs were frozen using three different methods. First, IPCs were immediately frozen at -80°C (-80°C group). Second, IPCs were initially placed into a Bicell freezing container before freezing at -80°C (BICELL group). Third, a vitrification method for oocytes and embryos was used (CRYOTOP group). Cell counting kit-8 (CCK-8) assay showed that cell viability was decreased in all groups after cryopreservation (P < 0.01). Corroboratively, the amount of adenosine triphosphate was markedly decreased after cryopreservation in all groups (P < 0.01). Immunofluorescence staining showed a reduced positive staining area for insulin in all cryopreservation groups. Furthermore, 4',6-diamidino-2-phenylindole and merged immunofluorescence images showed that cryopreserved cells appeared to be randomly reduced in the -80°C group and CRYOTOP group, while only the central region was visibly reduced in the BICELL group. Using immunohistochemical staining, IPCs after cryopreservation were shown to be positive for cleaved caspase-3 antibody in all groups. Finally, insulin secretion following glucose stimulation was significantly reduced in IPCs from all groups after cryopreservation (P < 0.01). In conclusion, IPCs may be too fragile for cryopreservation with accomplished methods and further investigations for a suitable preservation method are required.

A Novel Bone Substitute Based on Recombinant Type I Collagen for Reconstruction of Alveolar Cleft

This study aimed to examine the optimal cross-link density of recombinant peptide (RCP) particles, based on human collagen type I, for bone reconstruction in human alveolar cleft. Low- (group 1), medium- (group 2), and high- (group 3) cross-linked RCP particles were prepared by altering the duration of the heat-dependent dehydration reaction. Rat palatine fissures (n = 45), analogous to human congenital bone defects, were examined to evaluate the potential of bone formation by the three different RCP particles. Microcomputed tomography images were obtained to measure bone volume and bone mineral density at 4, 8, 12, and 16 weeks post grafting. Specimens were obtained for histological analysis at 16 weeks after grafting. Additionally, alkaline phosphatase and tartrate acid phosphatase staining were performed to visualize the presence of osteoblasts and osteoclasts. At 16 weeks, bone volume, bone mineral density, and new bone area measurements in group 2 were significantly higher than in any other group. In addition, the number of osteoblasts and osteoclasts on the new bone surface in group 2 was significantly higher than in any other group. Our results demonstrated that medium cross-linking was more suitable for bone formation—and could be useful in human alveolar cleft repairs as well.

Human Cadaveric Donor Cornea Derived Extra Cellular Matrix Microparticles for Minimally Invasive Healing/Regeneration of Corneal Wounds

Biological materials derived from extracellular matrix (ECM) proteins have garnered interest as their composition is very similar to that of native tissue. Herein, we report the use of human cornea derived decellularized ECM (dECM) microparticles dispersed in human fibrin sealant as an accessible therapeutic alternative for corneal anterior stromal reconstruction. dECM microparticles had good particle size distribution (≤10 µm) and retained the majority of corneal ECM components found in native tissue. Fibrin-dECM hydrogels exhibited compressive modulus of 70.83 ± 9.17 kPa matching that of native tissue, maximum burst pressure of 34.3 ± 3.7 kPa, and demonstrated a short crosslinking time of ~17 min. The fibrin-dECM hydrogels were found to be biodegradable, cytocompatible, non-mutagenic, non-sensitive, non-irritant, and supported the growth and maintained the phenotype of encapsulated human corneal stem cells (hCSCs) in vitro. In a rabbit model of anterior lamellar keratectomy, fibrin-dECM bio-adhesives promoted corneal re-epithelialization within 14 days, induced stromal tissue repair, and displayed integration with corneal tissues in vivo. Overall, our results suggest that the incorporation of cornea tissue-derived ECM microparticles in fibrin hydrogels is non-toxic, safe, and shows tremendous promise as a minimally invasive therapeutic approach for the treatment of superficial corneal epithelial wounds and anterior stromal injuries.

New cell delivery system CellSaic with adipose-derived stromal cells promotes functional angiogenesis in critical limb ischemia model mice

Current therapies for patients with critical limb ischemia have not reduced amputation risk owing to poor cell engraftment. The recombinant peptide Cellnest increases the engraftment rate of administered cells by forming a complex with the cells (CellSaic). We hypothesized that CellSaic containing adipose-derived stromal cells (ADSCs) could improve lower limb blood flow better than ADSCs alone, resulting in better transplanted cell engraftment. ADSCs were extracted from 8-week-old C57BL/6N mice. Thirty-two critical limb ischemia model mice were established by ligating femoral arteries. They were divided into CellSaic (n = 11), ADSC (n = 10), saline (n = 9), and Cellnest (n = 9) groups. Blood flow rate (affected side blood flow / healthy side blood flow × 100%) was evaluated using a laser Doppler blood flow meter every week. Mice were euthanized on day 28 for histological evaluation. Compared with the ADSC group (54.5 ± 17.2%), treated side blood flow rate of the CellSaic group (78.0 ± 24.9%) showed significant improvement on day 28 after administration (p < 0.05). CD31 staining showed significantly higher number of capillary vessels in the CellSaic group (53.0 ± 8.9 cells/mm³) than in the ADSC group (43.0 ± 6.8 cells/mm³) (p < 0.05). Fluorescent staining showed significantly higher number of arterioles containing both CD31 and αSMA double-positive cells in the CellSaic group than in the ADSC group (p < 0.05). CellSaic containing ADSCs exhibited superiority to ADSC transplantation alone in promoting functional angiogenesis, suggesting its potential in improving clinical outcomes of angiogenic therapy for ischemic limbs.

Bone formation potential of collagen type I-based recombinant peptide particles in rat calvaria defects

Introduction

This study aimed to examine the bone-forming ability of medium-cross-linked recombinant collagen peptide (mRCP) particles developedbased on human collagen type I, contains an arginyl-glycyl-aspartic acid-rich motif, fabricated as bone filling material, compared to that of the autologous bone graft.

Methods

Calvarial bone defects were created in immunodeficient rats though a surgical procedure. The rats were divided into 2 groups: mRCP graft and tibia bone graft (bone graft). The bone formation potential of mRCP was evaluated by micro-computed tomography and hematoxylin-eosin staining at 1, 2, 3, and 4 weeks after surgery, and the data were analyzed and compared to those of the bone graft.

Results

The axial volume-rendered images demonstrated considerable bony bridging with the mRCP graft, but there was no significant difference in the bone volume and bone mineral density between the mRCP graft and bone graft at 4 weeks. The peripheral new bone density was significantly higher than the central new bone density and the bottom side score was significantly higher than the top side score at early stage in the regenerated bone within the bone defects.

Conclusion

These results indicate that mRCP has a high potential of recruiting osteogenic cells, comparable to that of autologous bone chips.

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Bone formation potential of mRCP were comparable to that of autogenous bone.

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mRCP particles exhibit high new bone formation potential in the calvaria defect.

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Bone bridging was observed over the entire defect in mRCP graft at 4 weeks.

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mRCP has a high potential of recruiting osteogenic cells comparable to bone graft.

Generation of Insulin-Producing Cells from Canine Adipose Tissue-Derived Mesenchymal Stem Cells

The potential of mesenchymal stem cells (MSCs) to differentiate into nonmesodermal cells such as pancreatic beta cells has been reported. New cell-based therapy using MSCs for diabetes mellitus is anticipated as an alternative treatment option to insulin injection or islet transplantation in both human and veterinary medicine. Several protocols were reported for differentiation of MSCs into insulin-producing cells (IPCs), but no studies have reported IPCs generated from canine MSCs. The purpose of this study was to generate IPCs from canine adipose tissue-derived MSCs (AT-MSCs) in vitro and to investigate the effects of IPC transplantation on diabetic mice in vivo. Culturing AT-MSCs with the differentiation protocol under a two-dimensional culture system did not produce IPCs. However, spheroid-like small clusters consisting of canine AT-MSCs and human recombinant peptide μ-pieces developed under a three-dimensional (3D) culture system were successfully differentiated into IPCs. The generated IPCs under 3D culture condition were stained with dithizone and anti-insulin antibody. Canine IPCs also showed gene expression typical for pancreatic beta cells and increased insulin secretion in response to glucose stimulation. The blood glucose levels in streptozotocin-induced diabetic mice were decreased after injection with the supernatant of canine IPCs, but the hyperglycemic states of diabetic mice were not improved after transplanting IPCs subcutaneously or intramesenterically. The histological examination showed that the transplanted small clusters of IPCs were successfully engrafted to the mice and included cells positive for insulin by immunofluorescence. Several factors, such as the transplanted cell number, the origin of AT-MSCs, and the differentiation protocol, were considered potential reasons for the inability to improve the hyperglycemic state after IPC transplantation. These findings suggest that canine AT-MSCs can be differentiated into IPCs under a 3D culture system and IPC transplantation may be a new treatment option for dogs with diabetes mellitus.

Co-Microencapsulation of Islets and MSC CellSaics, Mosaic-Like Aggregates of MSCs and Recombinant Peptide Pieces, and Therapeutic Effects of Their Subcutaneous Transplantation on Diabetes

The subcutaneous transplantation of microencapsulated islets has been extensively studied as a therapeutic approach for type I diabetes. However, due to the lower vascular density and strong inflammatory response in the subcutaneous area, there have been few reports of successfully normalized blood glucose levels. To address this issue, we developed mosaic-like aggregates comprised of mesenchymal stem cells (MSCs) and recombinant peptide pieces called MSC CellSaics, which provide a continuous release of angiogenic factors and anti-inflammatory cytokines. Our previous report revealed that the diabetes of immunodeficient diabetic model mice was reversed by the subcutaneous co-transplantation of the MSC CellSaics and rat islets. In this study, we focused on the development of immune-isolating microcapsules to co-encapsulate the MSC CellSaics and rat islets, and their therapeutic efficiency via subcutaneous transplantation into immunocompetent diabetic model mice. As blood glucose level was monitored for 28 days following transplantation, the normalization rate of the new immuno-isolating microcapsules was confirmed to be significantly higher than those of the microcapsules without the MSC CellSaics, and the MSC CellSaics transplanted outside the microcapsules (p < 0.01). Furthermore, the number of islets required for the treatment was reduced. In the stained sections, a larger number/area of blood vessels was observed around the new immuno-isolating microcapsules, which suggests that angiogenic factors secreted by the MSC CellSaics through the microcapsules function locally for their enhanced efficacy.

A New Islet Transplantation Method Combining Mesenchymal Stem Cells with Recombinant Peptide Pieces, Microencapsulated Islets, and Mesh Bags

Microencapsulated islet transplantation was widely studied as a promising treatment for type 1 diabetes mellitus. However, micro-encapsulated islet transplantation has the following problems—early dysfunction of the islets due to the inflammatory reaction at the transplantation site, and hyponutrition and hypoxia due to a lack of blood vessels around the transplantation site, and difficulty in removal of the islets. On the other hand, we proposed a cell transplantation technique called CellSaic, which was reported to enhance the vascular induction effect of mesenchymal stem cells (MSCs) in CellSaic form, and to enhance the effect of islet transplantation through co-transplantation. Therefore, we performed islet transplantation in diabetic mice by combining three components—microencapsulated islets, MSC-CellSaic, and a mesh bag that encapsulates them and enables their removal. Mesh pockets were implanted in the peritoneal cavity of Balb/c mice as implantation sites. After 4 weeks of implantation, a pocket was opened and transplanted with (1) pancreatic islets, (2) microencapsulated islets, and (3) microencapsulated islets + MSC-CellSaic. Four weeks of observation of blood glucose levels showed that the MSC-CellSaic co-transplant group showed a marked decrease in blood glucose levels, compared to the other groups. A three-component configuration of microcapsules, MSC-CellSaic, and mesh bag was shown to enhance the efficacy of islet transplantation.

Enhancement of Cellular Adhesion and Proliferation in Human Mesenchymal Stromal Cells by the Direct Addition of Recombinant Collagen I Peptide to the Culture Medium

Mesenchymal stromal cells (MSCs) have considerable potential for a wide range of clinical applications and regenerative medicine and cell therapy. As a consequence, there is considerable interest in developing robust culture methods for producing large number of MSCs for use in repair of injured tissues or treatment of diseases. In general, tissue culture plates or flasks that have been precoated with substrates derived from animal tissues are used in the production of MSCs. However, these substrates can potentially cause serious problems due to contamination of the MSCs with animal-derived components. In this study, we evaluated the use of a type I collagen-based recombinant peptide (RCP) for MSC culture in an attempt to avoid the problems associated with animal cell-derived substances. This RCP is xeno free, has an increased RGD (Arg–Gly–Asp) sequence, and has high molecular weight uniformity. The effect of RCP on promotion of cellular adhesion and proliferation of MSCs was investigated in cultures in which RCP was included in the culture medium. The effects of RCP on promotion of cellular adhesion and proliferation of MSCs were investigated by comparing cultures in which the additive was present in the culture medium and those where the culture plates were coated with RCP. In addition, changes in gene expression profiles during cell culture were monitored by real time-polymerase chain reaction. Our analyses showed that RCP enhanced cellular adhesion and proliferation in cultures in which the additive was included in the culture medium. Our findings indicate that adding RCP to the culture medium could save time and cost in MSC culture. Our gene expression analysis indicated that RCP enhanced expression of genes encoding proteins associated with the extracellular matrix and cell adhesion.

Transplantation of dedifferentiated fat cells combined with a biodegradable type I collagen-recombinant peptide scaffold for critical-size bone defects in rats

Tissue engineering is a promising approach to supplement existing treatment strategies for craniofacial bone regeneration. In this study, a type I collagen scaffold made from a recombinant peptide (RCP) with an Arg-Gly-Asp motif was developed, and its effect on regeneration in critical-size mandibular bone defects was evaluated. Additionally, the combined effect of the scaffold and lipid-free dedifferentiated fat (DFAT) cells was assessed. Briefly, DFAT cells were separated from mature adipocytes by using a ceiling culture technique based on buoyancy. A 3 cm × 4 cm critical-size bone defect was created in the rat mandible, and regeneration was evaluated by using RCP with DFAT cells. Then, cultured DFAT cells and adipose-derived stem cells (ASCs) were seeded onto RCP scaffolds (DFAT/RCP and ASC/RCP) and implanted into the bone defects. Micro-computed tomography imaging at 8 weeks after implantation showed significantly greater bone regeneration in the DFAT/RCP group than in the ASC/RCP and RCP-alone groups. Similarly, histological analysis showed significantly greater bone width in the DFAT/RCP group than in the ASC/RCP and RCP-alone groups. These findings suggest that DFAT/RCP is effective for bone formation in critical-size bone defects and that DFAT cells are a promising source for bone regeneration.

The Differences in the Characteristics of Insulin-producing Cells Using Human Adipose-tissue Derived Mesenchymal Stem Cells from Subcutaneous and Visceral Tissues

The aim of this study was to investigate the characteristics of insulin producing cells (IPCs) differentiated from adipose-tissue derived stem cells (ADSCs) isolated from human subcutaneous and visceral adipose tissues and identify ADSCs suitable for differentiation into efficient and functional IPCs. Subcutaneous and visceral adipose tissues collected from four (4) patients who underwent digestive surgeries at The Tokushima University (000035546) were included in this study. The insulin secretion of the generated IPCs was investigated using surface markers by: fluorescence activated cell sorting (FACS) analysis; cytokine release; proliferation ability of ADSCs; in vitro (glucose-stimulated insulin secretion: (GSIS) test/in vivo (transplantation into streptozotocin-induced diabetic nude mice). The less fat-related inflammatory cytokines secretions were observed (P < 0.05), and the proliferation ability was higher in the subcutaneous ADSCs (P < 0.05). Insulin expression and GISI were higher in the subcutaneous IPCs (P < 0.01 and P < 0.05, respectively). The hyperglycaemic state of all mice that received IPCs from subcutaneous fat tissue converted into normo-glycaemia in thirty (30) days post-transplantation (4/4,100%). Transplanted IPCs were stained using anti-insulin and anti-human leukocyte antigen antibodies. The IPCs generated from the ADSCs freshly isolated from the human fat tissue had sufficient insulin secreting ability in vitro and in vivo.

In vitro and in vivo effects of insulin-producing cells generated by xeno-antigen free 3D culture with RCP piece

To establish widespread cell therapy for type 1 diabetes mellitus, we aimed to develop an effective protocol for generating insulin-producing cells (IPCs) from adipose-derived stem cells (ADSCs). We established a 3D culture using a human recombinant peptide (RCP) petaloid μ-piece with xeno-antigen free reagents. Briefly, we employed our two-step protocol to differentiate ADSCs in 96-well dishes and cultured cells in xeno-antigen free reagents with 0.1 mg/mL RCP μ-piece for 7 days (step 1), followed by addition of histone deacetylase inhibitor for 14 days (step 2). Generated IPCs were strongly stained with dithizone, anti-insulin antibody at day 21, and microstructures resembling insulin secretory granules were detected by electron microscopy. Glucose stimulation index (maximum value, 4.9) and MAFA mRNA expression were significantly higher in 3D cultured cells compared with conventionally cultured cells (P < 0.01 and P < 0.05, respectively). The hyperglycaemic state of streptozotocin-induced diabetic nude mice converted to normoglycaemic state around 14 days after transplantation of 96 IPCs under kidney capsule or intra-mesentery. Histological evaluation revealed that insulin and C-peptide positive structures existed at day 120. Our established xeno-antigen free and RCP petaloid μ-piece 3D culture method for generating IPCs may be suitable for clinical application, due to the proven effectiveness in vitro and in vivo.

Petaloid recombinant peptide enhances in vitro cartilage formation by synovial mesenchymal stem cells

In vitro chondrogenesis of mesenchymal stem cells (MSCs) mimics in vivo chondrogenesis of MSCs. However, the size of the cartilage pellets that can be attained in vitro is limited by current methods; therefore, some modifications are required to obtain larger pellets. Petaloid pieces of recombinant peptide (petaloid RCP) have the advantage of creating spaces between cells in culture. The RCP used here is based on the alpha-1 sequence of human collagen type I and contains 12 Arg-Gly-Asp motifs. We examined the effect and mechanisms of adding petaloid RCP on the in vitro chondrogenesis of human synovial MSCs by culturing 125k cells with or without 0.125 mg petaloid RCP in chondrogenic medium for 21 days. The cartilage pellets were sequentially analyzed by weight, sulfated glycosaminoglycan content, DNA retention, and histology. Petaloid RCP significantly increased the weight of the cartilage pellets: The petaloid RCP group weighed 7.7 ± 1.2 mg (n = 108), whereas the control group weighed 5.3 ± 1.6 mg. Sulfated glycosaminoglycan and DNA contents were significantly higher in the petaloid RCP group than in the control group. Light and transmission electron microscopy images showed that the petaloid RCP formed the framework of the pellet at day 1, the framework was broken by production of cartilage matrix by the synovial MSCs at day 7, and the cartilage pellet grew larger, with diffuse petaloid RCP remaining, at day 21. Therefore, petaloid RCP formed a framework for the pellet, maintained a higher cell number, and promoted in vitro cartilage formation of synovial MSCs. © 2018 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. J Orthop Res 37:1350-1357, 2019.

CellSaic, A Cell Aggregate-Like Technology Using Recombinant Peptide Pieces for MSC Transplantation

In the field of stem cell therapy, research on the application of Mesenchymal Stem Cells (MSCs) has flourished because of the various functions. On the other hand, research on the method of cell transplantation has developed from the administration of cell suspensions to cell-sheet engineering and 3D technology. In the trend, a cell transplantation platform named CellSaic, which is a combination of xeno-free recombinant scaffolds in a cell aggregate-like shape, was developed. CellSaic is the cell trans-plantation platform that can prevent the central necrosis within cell aggregates by arranging the cells and petaloid pieces of Recombinant Peptide (RCP) in a mosaic. The prevention of central necrosis is the most significant advantage over other 3D culture systems. This review details the unique characteristics of CellSaic including safety examination results and describes its future application for MSC transplantation. Particularly, in the application of MSCs, it has been reported that the MSC CellSaics increased the effect on improving various symptoms compared with MSCs only in the application of the therapy to Inflamma-tory Bowel Disease (IBD), cerebral infarction, bone cartilage regeneration in joints, and islet transplanta-tion. In accordance with the “One Health” concept, it is anticipated that this technology is expected to con-tribute to companion animal therapy and human therapy in the future.

The Optimization of the Prevascularization Procedures for Improving Subcutaneous Islet Engraftment

BACKGROUND

Subcutaneous islet transplantation is associated with minimal invasiveness, but poor vascularization. Thus, the optimization of the prevascularization procedures is crucial for improving the outcomes. Although the effectiveness of basic fibroblast growth factor (bFGF) was reported, the optimal procedures remain unclear. We sought to optimize the prevascularization procedures including the use of a novel scaffold, recombinant peptide (RCP).

METHODS

Devices containing various amount of bFGF with/without heparin or RCP were implanted into the subcutaneous space of diabetic C57BL/6 mice. Syngeneic islets were transplanted into the prevascularized space. Blood glucose, intraperitoneal glucose tolerance, and immunohistochemistry were evaluated.

RESULTS

The cure rates in all the device groups irrespective of bFGF doses were considerably higher than in the nondevice group. The cure rate in the bFGF0 group was unexpectedly higher than that in the subcutaneous islet transplant alone group (the None group) (57.1% vs 28.6%). Glucose tolerance was ameliorated in the bFGF10(-), 10(+) and 15(-) groups. The number of von Willebrand factor-positive vessels in the bFGF10(+) group was significantly higher than that in the None and bFGF0 groups (P < 0.01). Taken together, the bFGF10(+) group was considered to have received optimized procedures. In a marginal graft model, the efficiency in the RCP group was better than that in the bFGF10(+) group, furthermore, comparable to that in the intraportal transplantation group. Unlike bFGF, no bleeding and effusion were observed in the RCP group.

CONCLUSIONS

These results suggest that optimizing biomaterials to induce efficient prevascularization could be a novel strategy for improving subcutaneous islet transplantation.

An on-site preparable, novel bone-grafting complex consisting of human platelet-rich fibrin and porous particles made of a recombinant collagen-like protein

Platelet‐rich fibrin (PRF) is widely used in regenerative medicine. Nonetheless, major issues include its controversial effects on bone regeneration and a lack of quality‐assured glass tubes required for coagulation. We used porous particles (FBG) comprising a recombinant RGD motif‐enriched collagen I‐like protein to activate the coagulation pathway and examined the effects of the resulting PRF–FBG complex on bone regeneration. Human whole‐blood samples were mixed with FBG in plastic tubes and centrifuged to prepare a PRF–FBG complex. Platelet‐derived growth factor‐BB (PDGF‐BB) levels and cell growth activity were determined by ELISA and a bioassay using osteoblasts. Bone regenerative activity was assessed using a mouse model of calvarial bone defect. FBG facilitated PRF‐like matrix formation during centrifugation. In this PRF–FBG complex, the microstructure of fibrin fibers was similar to that of PRF prepared conventionally in glass tubes. PDGF‐BB levels and mitogenic action were not significantly influenced by FBG. In the bone defect model, although PRF did not exert any significant positive effects on its own, in combination with FBG, it synergistically stimulated new bone formation. This study demonstrated that incorporation of FBG into whole‐blood samples induces PRF formation without the aid of glass tubes. The resulting PRF–FBG complex could be a promising bone grafting material in clinical settings. © 2018 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1420–1430, 2019.

The Therapeutic Effects of Adipose-Derived Stem Cells and Recombinant Peptide Pieces on Mouse Model of DSS Colitis

Cell therapies using adipose-derived stem cells (ADSCs) have been used to treat inflammatory bowel disease (IBD) in human and dog. We previously reported the CellSaic technique, which uses a recombinant scaffold to enhance the efficacy of cell therapy. To examine whether this technique can be applied to cell therapy for colitis, we evaluated the efficacy of CellSaic in colitis mouse models. Colitis mouse models were developed by administering dextran sulfate sodium (DSS) to C57BL/6 mice for 7 days. Then CellSaic comprising human/canine ADSCs (1.2 × 10⁶ cells) or human/canine ADSCs only (1.2 × 10⁶ cells) were administered to the mice. The body weights were measured, and the colon length measurements and histological evaluations were conducted at 7 days after administration. After in vitro culture of human ADSC (hADSC) CellSaic and hADSC spheroids in medium containing TNFα, the levels of the anti-inflammatory protein TSG-6 in each supernatant were measured. Furthermore, we conducted tumorigenicity and general toxicity tests of canine ADSC (cADSC) CellSaic in NOG mice for 8 weeks. In the colitis mouse models, the ADSC CellSaic group presented recovery of body weight and colon length compared with the ADSC-only group. Histological analysis showed that ADSC CellSaic decreased the number of inflammatory cells and repaired ulceration. In vitro, hADSC CellSaic secreted 3.1-fold more TSG-6 than the hADSCs. In addition, tumorigenicity and general toxicity of cADSC CellSaic were not observed. This study suggests that human and canine ADSC CellSaic has a therapeutic effect of colitis in human and dogs.

Human Recombinant Peptide Sponge Enables Novel, Less Invasive Cell Therapy for Ischemic Stroke

Bone marrow stromal cell (BMSC) transplantation has the therapeutic potential for ischemic stroke. However, it is unclear which delivery routes would yield both safety and maximal therapeutic benefits. We assessed whether a novel recombinant peptide (RCP) sponge, that resembles human collagen, could act as a less invasive and beneficial scaffold in cell therapy for ischemic stroke. BMSCs from green fluorescent protein-transgenic rats were cultured and Sprague–Dawley rats were subjected to permanent middle cerebral artery occlusion (MCAo). A BMSC-RCP sponge construct was transplanted onto the ipsilateral intact neocortex 7 days after MCAo. A BMSC suspension or vehicle was transplanted into the ipsilateral striatum. Rat motor function was serially evaluated and histological analysis was performed 5 weeks after transplantation. The results showed that BMSCs could proliferate well in the RCP sponge and the BMSC-RCP sponge significantly promoted functional recovery, compared with the vehicle group. Histological analysis revealed that the RCP sponge provoked few inflammatory reactions in the host brain. Moreover, some BMSCs migrated to the peri-infarct area and differentiated into neurons in the BMSC-RCP sponge group. These findings suggest that the RCP sponge may be a promising candidate for animal protein-free scaffolds in cell therapy for ischemic stroke in humans.