Dual-Purpose Bioreactors to Monitor Noninvasive Physical and Biochemical Markers of Kidney and Liver Scaffold Recellularization

Analysis of perfusion-based bioreactors for organ engineering and a detailed evaluation of physical and biochemical parameters that measure dynamic changes within maturing cell-laden scaffolds are critical components of ex vivo tissue development that remain understudied topics in the tissue and organ engineering literature. Intricately designed bioreactors that house developing tissue are critical to properly recapitulate the in vivo environment, deliver nutrients within perfused media, and monitor physiological parameters of tissue development. Herein, we provide an in-depth description and analysis of two dual-purpose perfusion bioreactors that improve upon current bioreactor designs and enable comparative analyses of ex vivo scaffold recellularization strategies and cell growth performance during long-term maintenance culture of engineered kidney or liver tissues. Both bioreactors are effective at maximizing cell seeding of small-animal organ scaffolds and maintaining cell survival in extended culture. We further demonstrate noninvasive monitoring capabilities for tracking dynamic changes within scaffolds as the native cellular component is removed during decellularization and model human cells are introduced into the scaffold during recellularization and proliferate in maintenance culture. We found that hydrodynamic pressure drop (ΔP) across the retained scaffold vasculature is a noninvasive measurement of scaffold integrity. We further show that ΔP, and thus resistance to fluid flow through the scaffold, decreases with cell loss during decellularization and correspondingly increases to near normal values for whole organs following recellularization of the kidney or liver scaffolds. Perfused media may be further sampled in real time to measure soluble biomarkers (e.g., resazurin, albumin, or kidney injury molecule-1) that indicate degree of cellular metabolic activity, synthetic function, or engraftment into the scaffold. Cell growth within bioreactors is validated for primary and immortalized cells, and the design of each bioreactor is scalable to accommodate any three-dimensional scaffold (e.g., synthetic or naturally derived matrix) that contains conduits for nutrient perfusion to deliver media to growing cells and monitor noninvasive parameters during scaffold repopulation, broadening the applicability of these bioreactor systems.

MEK and TGF-beta Inhibition Promotes Reprogramming without the Use of Transcription Factor

The possibility of replacing the originally discovered and widely used DNA reprogramming transcription factors is stimulating enormous effort to identify more effective compounds that would not alter the genetic information. Here, we describe the generation of induced pluripotent stem cells (iPSc) from head-derived primary culture of mouse embryonic cells using small chemical inhibitors of the MEK and TGF-beta pathways without delivery of exogenous transcription factors. These iPSc express standard pluripotency markers and retain their potential to differentiate into cells of all germ layers. Our data indicate that head-derived embryonic neural cells might have the reprogramming potential while neither the same primary cells cultivated over five passages in vitro nor a cell population derived from adult brain possesses this capacity. Our results reveal the potential for small molecules to functionally replace routinely used transcription factors and lift the veil on molecular regulation controlling pluripotency. The conditions described here could provide a platform upon which other genome non integrative and safer reprogramming processes could be developed. This work also shows novel potential for developing embryonic neural cells.

Co-expression of TTF-1 and neuroendocrine markers in the human fetal lung and pulmonary neuroendocrine tumors

The expression pattern of thyroid transcription factor 1 (TTF-1) and neuroendocrine markers, neuron cell adhesion molecule (NCAM; CD56), chromogranin A (CgA) and synaptophysin (Syp), of different lung cell lineages was histologically analyzed in 15 normal human fetal lungs and 12 neuroendocrine tumors (NETs) using immunohistochemical methods. During pseudoglandular phase strong nuclear TTF-1 staining was detected in the columnar nonciliated epithelial cells, while NCAM, CgA and Syp had a moderate expression in the proximal airways and mild expression in the distal airways. Neuroendocrine cells (NECs) in proximal lung airway were co-localizing TTF-1 and other neuroendocrine markers while neuroendocrine bodies (NEBs) exhibit only staining with NCAM and Syp. In the canalicular phase TTF-1 nuclear staining was expressed only in several epithelial cells in proximal airways, while budding airways epithelium showed strong TTF-1 expression. Expression of NCAM, CgA and Syp in this phase equals the one in pseudoglandular phase. NEBs cells were co-localizing TTF-1 and NCAM in proximal airways and few NECs in distal airway were co-localizing TTF-1 and Syp. TTF-1 staining in the saccular phase was limited to subsets of epithelial cells in the proximal airways with stronger positivity in the distal airways. NCAM expression is moderate only in proximal airways, while Syp and CgA show mild expression in proximal and distal airways. NECs were co-localizing TTF-1 and NCAM in proximal lung airway. With regard to NECs, all small cell lung cancer (SCLC) cells had strong TTF-1, NCAM, Syp and CgA positivity and TTF-1 co-localized with other neuroendocrine markers. All pulmonary typical carcinoids were TTF-1 negative, while pulmonary atypical carcinoids were focal positive for TTF-1 and some neoplastic cells co-localized TTF-1 with neuroendocrine markers. Our results indicate that TTF-1 expression in NECs suggests a possible role in their normal development and differentiation. Our results also indicate that possible cell of origin for poorly differentiated SCLC and some atypical carcinoid could be a progenitor cell in neuroendocrine lineage while in typical carcinoids possible cell of origin is localized in terminally differentiated NECs.

The appendix as a viable source of neural progenitor cells to functionally innervate bioengineered gastrointestinal smooth muscle tissues

Appendix-derived neural progenitor cells (NPCs) have both neurogenic and gliogenic potential, but use of these cells for enteric neural cell therapy has not been addressed. The objective of this study was to determine whether NPCs obtained from the appendix would differentiate into enteric neural subsets capable of inducing neurotransmitter-mediated smooth muscle cell (SMC) contraction and relaxation. NPCs were isolated from the appendix and small intestine (SI) of rabbits. Bioengineered internal anal sphincter constructs were developed using the same source of smooth muscle and innervated with NPCs derived from either the appendix or SI. Innervated constructs were assessed for neuronal differentiation markers through Western blots and immunohistochemistry, and functionality was assessed through force-generation studies. Expression of neural and glial differentiation markers was observed in constructs containing appendix- and SI-derived NPCs. The addition of acetylcholine to both appendix and SI constructs caused a robust contraction that was decreased by pretreatment with the neural inhibitor tetrodotoxin (TTX). Electrical field stimulation caused relaxation of constructs that was completely abolished in the presence of TTX and significantly reduced on pretreatment with nitric oxide synthase inhibitor (Nω-nitro-l-arginine methyl ester hydrochloride [l-NAME]). These data indicate that in the presence of identical soluble factors arising from intestinal SMCs, enteric NPCs derived from the appendix and SI differentiate in a similar manner and are capable of responding to physiological stimuli. This coculture paradigm could be used to explore the nature of the soluble factors derived from SMCs and NPCs in generating specific functional innervations.

SIGNIFICANCE

This study demonstrates the ability of neural stem cells isolated from the appendix to differentiate into mature functional enteric neurons. The differentiation of neural stem cells from the appendix is similar to differentiation of neural stem cells derived from the gastrointestinal tract. The appendix is a vestigial organ that can be removed with minimal clinical consequence through laparoscopy. Results presented in this paper indicate that the appendix is a potential source of autologous neural stem cells required for cell therapy for the gastrointestinal tract.

Multi-lineage differentiation of human umbilical cord Wharton's Jelly Mesenchymal Stromal Cells mediates changes in the expression profile of stemness markers

Wharton's Jelly- derived Mesenchymal stem cells (WJ-MSCs) have gained interest as an alternative source of stem cells for regenerative medicine because of their potential for self-renewal, differentiation and unique immunomodulatory properties. Although many studies have characterized various WJ-MSCs biologically, the expression profiles of the commonly used stemness markers have not yet been addressed. In this study, WJ-MSCs were isolated and characterized for stemness and surface markers expression. Flow cytometry, immunofluorescence and qRT-PCR analysis revealed predominant expression of CD29, CD44, CD73, CD90, CD105 and CD166 in WJ-MSCs, while the hematopoietic and endothelial markers were absent. Differential expression of CD 29, CD90, CD105 and CD166 following adipogenic, osteogenic and chondrogenic induction was observed. Furthermore, our results demonstrated a reduction in CD44 and CD73 expressions in response to the tri-lineage differentiation induction, suggesting that they can be used as reliable stemness markers, since their expression was associated with undifferentiated WJ-MSCs only.

Umbilical Cord Blood-Derived Mononuclear Cells Exhibit Pericyte-Like Phenotype and Support Network Formation of Endothelial Progenitor Cells In Vitro

Umbilical cord blood represents a promising cell source for pro-angiogenic therapies. The present study examined the potential of mononuclear cells (MNCs) from umbilical cord blood to support endothelial progenitor cell (EPC) microvessel formation. MNCs were isolated from the cord blood of 20 separate donors and selected for further characterization based upon their proliferation potential and morphological resemblance to human vascular pericytes (HVPs). MNCs were screened for their ability to support EPC network formation using an in vitro assay (Matrigel™) as well as a reductionist, coculture system consisting of no additional angiogenic cytokines beyond those present in serum. In less than 15% of the isolations, we identified a population of highly proliferative MNCs that phenotypically resembled HVPs as assessed by expression of PDGFR-β, NG2, α-SMA, and ephrin-B2. Within a Matrigel™ system, MNCs demonstrated pericyte-like function through colocalization to EPC networks and similar effects as HVPs upon total EPC tubule length (p = 0.95) and number of branch points (p = 0.93). In a reductionist coculture system, MNCs served as pro-angiogenic mural cells by supporting EPC network formation to a significantly greater extent than HVP cocultures, by day 14 of coculture, as evidenced through EPC total tubule length (p < 0.0001) and number of branch points (p < 0.0001). Our findings are significant as we demonstrate mural cell progenitors can be isolated from umbilical cord blood and develop culture conditions to support their use in microvascular tissue engineering applications.

DMSO efficiently down regulates pluripotency genes in human embryonic stem cells during definitive endoderm derivation and increases the proficiency of hepatic differentiation

Background

Definitive endoderm (DE) is one of the three germ layers which during in vivo vertebrate development gives rise to a variety of organs including liver, lungs, thyroid and pancreas; consequently efficient in vitro initiation of stem cell differentiation to DE cells is a prerequisite for successful cellular specification to subsequent DE-derived cell types [1, 2]. In this study we present a novel approach to rapidly and efficiently down regulate pluripotency genes during initiation of differentiation to DE cells by addition of dimethyl sulfoxide (DMSO) to Activin A-based culture medium and report its effects on the downstream differentiation to hepatocyte-like cells.

Materials and Methods

Human embryonic stem cells (hESC) were differentiated to DE using standard methods in medium supplemented with 100ng/ml of Activin A and compared to cultures where DE specification was additionally enhanced with different concentrations of DMSO. DE cells were subsequently primed to generate hepatic-like cells to investigate whether the addition of DMSO during formation of DE improved subsequent expression of hepatic markers. A combination of flow cytometry, real-time quantitative reverse PCR and immunofluorescence was applied throughout the differentiation process to monitor expression of pluripotency (POUF5/OCT4 & NANOG), definitive endoderm (SOX17, CXCR4 & GATA4) and hepatic (AFP & ALB) genes to generate differentiation stage-specific signatures.

Results

Addition of DMSO to the Activin A-based medium during DE specification resulted in rapid down regulation of the pluripotency genes OCT4 and NANOG, accompanied by an increase expression of the DE genes SOX17, CXCR4 and GATA4. Importantly, the expression level of ALB in DMSO-treated cells was also higher than in cells which were differentiated to the DE stage via standard Activin A treatment.

In vitro reprogramming of pancreatic alpha cells towards a beta cell phenotype following ectopic HNF4α expression

There is currently a shortage of organ donors available for pancreatic beta cell transplantation into diabetic patients. An alternative source of beta cells is pre-existing pancreatic cells. While we know that beta cells can arise directly from alpha cells during pancreatic regeneration we do not understand the molecular basis for the switch in phenotype. The aim of the present study was to investigate if hepatocyte nuclear factor 4 alpha (HNF4α), a transcription factor essential for a normal beta cell phenotype, could induce the reprogramming of alpha cells towards potential beta cells. We utilised an in vitro model of pancreatic alpha cells, the murine αTC1-9 cell line. We initially characterised the αTC1-9 cell line before and following adenovirus-mediated ectopic expression of HNF4α. We analysed the phenotype at transcript and protein level and assessed its glucose-responsiveness. Ectopic HNF4α expression in the αTC1-9 cell line induced a change in morphology (1.7-fold increase in size), suppressed glucagon expression, induced key beta cell-specific markers (insulin, C-peptide, glucokinase, GLUT2 and Pax4) and pancreatic polypeptide (PP) and enabled the cells to secrete insulin in a glucose-regulated manner. In conclusion, HNF4α reprograms alpha cells to beta-like cells.

Melatonin promotes hepatic differentiation of human dental pulp stem cells: clinical implications for the prevention of liver fibrosis

Melatonin's effect on hepatic differentiation of stem cells remains unclear. The aim of this study was to investigate the action of melatonin on hepatic differentiation as well as its related signaling pathways of human dental pulp stem cells (hDPSCs) and to examine the therapeutic effects of a combination of melatonin and hDPSC transplantation on carbon tetrachloride (CCl4 )-induced liver fibrosis in mice. In vitro hepatic differentiation was assessed by periodic acid-Schiff (PAS) staining and mRNA expression for hepatocyte markers. Liver fibrosis model was established by injecting 0.5 mL/kg CCl4 followed by treatment with melatonin (5 mg/kg, twice a week) and hDPSCs. In vivo therapeutic effects were evaluated by histopathology and by means of liver function tests including measurement of alanine transaminase (ALT), aspartate transaminase (AST), and ammonia levels. Melatonin promoted hepatic differentiation based on mRNA expression of differentiation markers and PAS-stained glycogen-laden cells. In addition, melatonin increased bone morphogenic protein (BMP)-2 expression and Smad1/5/8 phosphorylation, which was blocked by the BMP antagonist noggin. Furthermore, melatonin activated p38, extracellular signal-regulated kinase (ERK), and nuclear factor-κB (NF-κB) in hDPSCs. Melatonin-induced hepatic differentiation was attenuated by inhibitors of BMP, p38, ERK, and NF-κB. Compared to treatment of CCl4 -injured mice with either melatonin or hDPSC transplantation alone, the combination of melatonin and hDPSC significantly suppressed liver fibrosis and restored ALT, AST, and ammonia levels. For the first time, this study demonstrates that melatonin promotes hepatic differentiation of hDPSCs by modulating the BMP, p38, ERK, and NF-κB pathway. Combined treatment of grafted hDPSCs and melatonin could be a viable approach for the treatment of liver cirrhosis.

[CHARACTERISTICS OF NEW MESENCHYMAL STEM CELL LINE DERIVED FROM HUMAN EMBRYONIC STEM CELLS]

New nonimmortalized fibroblast-like cell line SC6-MSC has been obtained from a line of human embryonic stem cells (ESC)--SC6. Numerical and structural karyotypic analysis has shown hypodiploidy karyotypic: 45, X0 in this line. The average cell population doublings time, for SC6-MSC is 26.0 ± 0.4 h at the 8th passage and 82.0 ± 9.2 h at the 18th passage. The growth curves showed active proliferation for 8-10 passages with a consequent gradual decrease of proliferative activity, which ended to 20th passage. To determine the line's status, the analysis of the surface markers by flow cytometry was carried out. We have revealed the expression of surface antigens CD44, CD73, CD90, CD105 and HLA-ABC characteristic for human MSC, and the absence of CD34 and HLA-DR expression. However, the level of expression of surface markers CD90 and CD105 was significantly lower in comparison with other MSC lines including the line SC5-MSC derived from the line human ESC-SC5. Immunofluorescence analysis of the expression of the surface markers and transcription factor Oct-4 characteristic for human embryonic stem cells showed the absence of Oct-4 expression and the presence of SSEA-4 and TRA-1-60 expression, which is characteristic for a number of MSC lines with normal karyotype. Immunofluorescence analysis has shown the presence of the markers of early differentiation in the derivates of three germ layers, characteristic for human ESC, which in corresponding microenvironments may allow MSC to be useful for reparation of tissue injures. The directed osteogenic and chondrogenic differentiation of line SC6-MSC has shown. However, no directed adipogenic differentiation of this line has been found. The obtained results with high probability may indicate what alteration of chromosomal and, accordingly, gene balance, in line SC6-MSC with karyotype 45, X0 resulted in decrease in differential potential, in expression CD90, associated in particular with the processes of differentiation and aging of cells.

[CHARACTERISTIC OF THE CELLULAR SPHEROIDS, DERIVED FROM MESENCHYMAL STEM CELL LINES FROM BONE MARROW AND MUSCLE OF LIMB OF EARLY HUMAN EMBRYO]

Cellular spheroids were derived from mesenchymal stem cell lines derived from 5-6-weeks embryo from different tissues of 5-6-week human embryo: bone marrow (FetMSC) and muscle of limb (M-FetMSC). Comparative analysis of the characteristics of these lines has been performed with 2D culturing in monolayer and 3D culturing in spheroids. The characteristics of cellular spheroids were obtained after 48 h after their formation from monolayer cultures on the 6th passage after decryopreservation. Spheroids in contrast to monolayer cultures are heterogeneous cell populations composed of fibroblast-like and epithelioid cells. Two-day spheroids are actively proliferating structure. Cell surface markers were analyzed using flow cytometry. Both in the monolayer cultures and cellular spheroids, this analysis has revealed the presence of expression of surface antigens CDD44, CD73, CD9O, CD105, HLA-ABC that are characteristic of human MSC, and the absence of expression if CD34 and HLA-DR. Nevertheless, the level of expression of CD90 and CD105 antigens was significantly lower in the spheroids as compared with corresponding monolayer cultures. Immunofluorescence and flow cytometry analysis of the expression of transcriptions factors and surface antigens characteristic of human embryonic stem cells showed the presence of expression of Sox-2 and SSEA-4 in 2D and 3D cultures. Lack of expression of Oct-4 in 2D cultures and its significant increase in 3D cultures has been found. Immunofluorescence analysis showed the presence of the markers of early differentiation in the derivates of three germ layers characteristic of human embryonic stem cells in the cellular spheroids of both lines, which coincides with 2D cultures of these lines. The directed osteogenic, chondrogenic and adipogenic differentiation of these lines has been shown. However, a number of differences has been found between monolayer cultures and spheroids. Adipogenic differentiation was more active in the cellular spheroids from cell line M-FetMSC a compared with corresponding monolayer cultures. Differences between the 2D and 3D cultures of both lines have been shown by the character of chondrogenic differentiation. The results obtained confirm the status of MSC for the cellular spheroids derived from monolayer cultured of cell lines FetMSC and M-FetMSC and apparently indicate a partial extension of their differentiation capacity as compared to monolayer cultured.

Inactivation of Fam20C in cells expressing type I collagen causes periodontal disease in mice

BACKGROUND

FAM20C is a kinase that phosphorylates secretory proteins. Previous studies have shown that FAM20C plays an essential role in the formation and mineralization of bone, dentin and enamel. The present study analyzed the loss-of-function effects of FAM20C on the health of mouse periodontal tissues.

METHODS

By crossbreeding 2.3 kb Col 1a1-Cre mice with Fam20Cfl/fl mice, we created 2.3 kb Col 1a1-Cre;Fam20Cfl/fl (cKO) mice, in which Fam20C was inactivated in the cells that express Type I collagen. We analyzed the periodontal tissues in the cKO mice using X-ray radiography, histology, scanning electron microscopy and immunohistochemistry approaches.

RESULTS

The cKO mice underwent a remarkable loss of alveolar bone and cementum, along with inflammation of the periodontal ligament and formation of periodontal pockets. The osteocytes and lacuno-canalicular networks in the alveolar bone of the cKO mice showed dramatic abnormalities. The levels of bone sialoprotein, osteopontin, dentin matrix protein 1 and dentin sialoprotein were reduced in the Fam20C-deficient alveolar bone and/or cementum, while periostin and fibrillin-1 were decreased in the periodontal ligament of the cKO mice.

CONCLUSION

Loss of Fam20C function leads to periodontal disease in mice. The reduced levels of bone sialoprotein, osteopontin, dentin matrix protein 1, dentin sialoprotein, periostin and fibrillin-1 may contribute to the periodontal defects in the Fam20C-deficient mice.

Tissue-engineered vascular grafts created from human induced pluripotent stem cells

The utility of human induced pluripotent stem cells (hiPSCs) to create tissue-engineered vascular grafts was evaluated in this study. hiPSC lines were first induced into a mesenchymal lineage via a neural crest intermediate using a serum-free, chemically defined differentiation scheme. Derived cells exhibited commonly known mesenchymal markers (CD90, CD105, and CD73 and negative marker CD45) and were shown to differentiate into several mesenchymal lineages (osteogenic, chondrogenic, and adipogenic). Functional vascular grafts were then engineered by culturing hiPSC-derived mesenchymal progenitor cells in a pulsatile bioreactor system over 8 weeks to induce smooth muscle cell differentiation and collagenous matrix generation. Histological analyses confirmed layers of calponin-positive smooth muscle cells in a collagen-rich matrix. Mechanical tests revealed that grafts had an average burst pressure of 700 mmHg, which is approximately half that of native veins. Additionally, studies revealed that karyotypically normal mesenchymal stem cell clones led to generation of grafts with predicted features of engineered vascular grafts, whereas derived clones having chromosomal abnormalities generated calcified vessel constructs, possibly because of cell apoptosis during culture. Overall, these results provide significant insight into the utility of hiPS cells for vascular graft generation. They pave the way for creating personalized, patient-specific vascular grafts for surgical applications, as well as for creating experimental models of vascular development and disease.

Osteogenic differentiation of human amniotic epithelial cells and its application in alveolar defect restoration

The present study investigated the detailed in vitro osteogenic differentiation process and in vivo bone regenerative property of human amniotic epithelial cells (hAECs). The in vitro osteogenic differentiation process of hAECs was evaluated by biochemical staining, real-time polymerase chain reaction, and immunofluorescence. Next, β-tricalcium phosphate (β-TCP) scaffolds alone or loaded with hAECs were implanted into the alveolar defects of rats. Micro-computed tomography evaluation and histologic studies were conducted. Our results validated the in vitro osteogenic capacity of hAECs by upregulation of Runx2, osterix, alkaline phosphatase, collagen I, and osteopontin, with positive biochemical staining for osteoblasts. An epithelial-mesenchymal transformation process might be involved in the osteogenic differentiation of hAECs by increased expression of transforming growth factor-β1. Our data also demonstrated that in vivo implantation of hAECs loaded on β-TCP scaffolds, not only improved bone regeneration by direct participation, but also reduced the early host immune response to the scaffolds. The presented data indicate that hAECs possess proper osteogenic differentiation potential and a modulatory influence on the early tissue remodeling process, making these cells a potential source of progenitor cells for clinical restoration of the alveolar defect.

Reprogramming human retinal pigmented epithelial cells to neurons using recombinant proteins

Somatic cells can be reprogrammed to an altered lineage by overexpressing specific transcription factors. To avoid introducing exogenous genetic material into the genome of host cells, cell-penetrating peptides can be used to deliver transcription factors into cells for reprogramming. Position-dependent C-end rule (CendR) cell- and tissue-penetrating peptides provide an alternative to the conventional cell-penetrating peptides, such as polyarginine. In this study, we used a prototypic, already active CendR peptide, RPARPAR, to deliver the transcription factor SOX2 to retinal pigmented epithelial (RPE) cells. We demonstrated that RPE cells can be directly reprogrammed to a neuronal fate by introduction of SOX2. Resulting neuronal cells expressed neuronal marker mRNAs and proteins and downregulated expression of RPE markers. Cells produced extensive neurites and developed synaptic machinery capable of dye uptake after depolarization with potassium. The RPARPAR-mediated delivery of SOX2 alone was sufficient to allow cell lineage reprogramming of both fetal and stem cell-derived RPE cells to become functional neurons.

Very late antigen-5 facilitates stromal progenitor cell differentiation into myofibroblast

Fibrotic disease is associated with abrogated stromal cell proliferation and activity. The precise identity of the cells that drive fibrosis remains obscure, in part because of a lack of information on their lineage development. To investigate the role of an early stromal progenitor cell (SPC) on the fibrotic process, we selected for, and monitored the stages of, fibroblast development from a previously reported free-floating anchorage-independent cell (AIC) progenitor population. Our findings demonstrate that organotypic pulmonary, cardiac, and renal fibroblast commitment follows a two-step process of attachment and remodeling in culture. Cell differentiation was confirmed by the inability of SPCs to revert to the free-floating state and functional mesenchymal stem/stromal cell (MSC) differentiation into osteoblast, adipocyte, chondrocyte, and fibroblastic lineages. The myofibroblastic phenotype was reflected by actin stress-fiber formation, α-smooth muscle production, and a greater than threefold increase in proliferative activity compared with that of the progenitors. SPC-derived pulmonary myofibroblasts demonstrated a more than 300-fold increase in fibronectin-1 (Fn1), collagen, type 1, α1, integrin α-5 (Itga5), and integrin β-1 (Itgb1) transcript levels. Very late antigen-5 (ITGA5/ITGB1) protein cluster formations were also prevalent on the differentiated cells. Normalized SPC-derived myofibroblast expression patterns reflected those of primary cultured lung myofibroblasts. Intratracheal implantation of pulmonary AICs into recipient mouse lungs resulted in donor cell FN1 production and evidence of epithelial derivation. SPC derivation into stromal tissue in vitro and in vivo and the observation that MSC and fibroblast lineages share a common ancestor could potentially lead to personalized antifibrotic therapies.

Carbon nanotube-collagen three-dimensional culture of mesenchymal stem cells promotes expression of neural phenotypes and secretion of neurotrophic factors

Microenvironments provided by three-dimensional (3-D) hydrogels mimic native tissue conditions, supplying appropriate physical cues for regulating stem cell behaviors. Here, we focused on carbon nanotubes (CNTs) dispersed within collagen hydrogels to provide 3-D microenvironmental conditions for mesenchymal stem cells (MSCs) in stimulating biological functions for neural regeneration. Small concentrations of CNTs (0.1-1wt.%) did not induce toxicity to MSCs, and even improved the proliferative potential of the cells. MSCs cultured within the CNT-collagen hydrogel expressed considerable levels of neural markers, including GAP43 and βIII tubulin proteins by immunostaining as well as GAP43 and synapse I genes by reverse transcriptase polymerase chain reaction (RT-PCR). Of note was that neurotrophic factors, particularly nerve growth factor and brain derived neurotrophic factor, were significantly promoted by the incorporation of CNTs as confirmed by RT-PCR and Western blot analysis. A model experiment involving neuritogenesis of PC12 cells influenced by those releasing neurotrophic factors from MSCs cultured within the CNT-collagen hydrogel demonstrated the significant enhancement in neurite outgrowth behaviors. Taken together, collagen hydrogel provides excellent 3-D conditions for MSC growth, and a small incorporation of CNTs within the hydrogel significantly stimulates MSC expression of neural markers and secretion of neurotrophic factors.

Spatial distribution of niche and stem cells in ex vivo human limbal cultures

Stem cells at the limbus mediate corneal epithelial regeneration and regulate normal tissue homeostasis. Ex vivo cultured limbal epithelial transplantations are being widely practiced in the treatment of limbal stem cell deficiency. In this report, we examined whether the limbal niche cells that nurture and regulate epithelial stem cells coexist in ex vivo limbal cultures. We also compared the inherent differences between explant and suspension culture systems in terms of spatial distribution of niche cells and their effect on epithelial stem cell proliferation, migration, and differentiation in vitro. We report that the stem cell content of both culture systems was similar, explaining the comparable clinical outcomes reported using these two methods. We also showed that the niche cells get expanded in culture and the nestin-positive cells migrate at the leading edges to direct epithelial cell migration in suspension cultures, whereas they are limited to the intact niche in explant cultures. We provide evidence that C/EBPδ-positive, p15-positive, and quiescent, label-retaining, early activated stem cells migrate at the leading edges to regulate epithelial cell proliferation in explant cultures, and this position effect is lost in early suspension cultures. However, in confluent suspension cultures, the stem cells and niche cells interact with each another, migrate in spiraling patterns, and self-organize to form three-dimensional niche-like compartments resembling the limbal crypts and thereby reestablish the position effect. These 3D-sphere clusters are enriched with nestin-, vimentin-, S100-, and p27-positive niche cells and p15-, p21-, p63α-, C/EBPδ-, ABCG2-, and Pax6-positive quiescent epithelial stem cells.

Intermittent PTHrP(1-34) exposure augments chondrogenesis and reduces hypertrophy of mesenchymal stromal cells

Phenotype instability and premature hypertrophy prevent the use of human mesenchymal stromal cells (MSCs) for cartilage regeneration. Aim of this study was to investigate whether intermittent supplementation of parathyroid hormone-related protein (PTHrP), as opposed to constant treatment, can beneficially influence MSC chondrogenesis and to explore molecular mechanisms below catabolic and anabolic responses. Human MSCs subjected to chondrogenic induction in high-density culture received PTHrP(1-34), forskolin, dbcAMP, or PTHrP(7-34) either constantly or via 6-h pulses (three times weekly), before proteoglycan, collagen type II, and X deposition; gene expression; and alkaline phosphatase (ALP) activity were assessed. While constant application of PTHrP(1-34) suppressed chondrogenesis of MSCs, pulsed application significantly increased collagen type 2 (COL2A1) gene expression and the collagen type II, proteoglycan, and DNA content of pellets after 6 weeks. Collagen type 10 (COL10A1) gene expression was little affected but Indian hedgehog (IHH) expression and ALP activity were significantly downregulated by pulsed PTHrP. A faster response to PTHrP exposure was recorded for ALP activity over COL2A1 regulation, suggesting that signal duration is critical for catabolic versus anabolic reactions. Stimulation of cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling by forskolin reproduced major effects of both treatment modes, whereas application of PTHrP(7-34) capable of protein kinase C (PKC) signaling was ineffective. Pulsed PTHrP exposure of MSCs stimulated chondrogenesis and reduced endochondral differentiation apparently uncoupling chondrogenic matrix deposition from hypertrophic marker expression. cAMP/PKA was the major signaling pathway triggering the opposing effects of both treatment modes. Intermittent application of PTHrP represents an important novel means to improve chondrogenesis of MSCs and may be considered as a supporting clinical-treatment mode for MSC-based cartilage defect regeneration.

Low-intensity pulsed ultrasound stimulation facilitates osteogenic differentiation of human periodontal ligament cells

Human periodontal ligament cells (hPDLCs) possess stem cell properties, which play a key role in periodontal regeneration. Physical stimulation at appropriate intensities such as low-intensity pulsed ultrasound (LIPUS) enhances cell proliferation and osteogenic differentiation of mesechymal stem cells. However, the impacts of LIPUS on osteogenic differentiation of hPDLCs in vitro and its molecular mechanism are unknown. This study was undertaken to investigate the effects of LIPUS on osteogenic differentiation of hPDLCs. HPDLCs were isolated from premolars of adolescents for orthodontic reasons, and exposed to LIPUS at different intensities to determine an optimal LIPUS treatment dosage. Dynamic changes of alkaline phosphatase (ALP) activities in the cultured cells and supernatants, and osteocalcin production in the supernatants after treatment were analyzed. Runx2 and integrin β1 mRNA levels were assessed by reverse transcription polymerase chain reaction analysis after LIPUS stimulation. Blocking antibody against integrinβ1 was used to assess the effects of integrinβ1 inhibitor on LIPUS-induced ALP activity, osteocalcin production as well as calcium deposition. Our data showed that LIPUS at the intensity of 90 mW/cm2 with 20 min/day was more effective. The ALP activities in lysates and supernatants of LIPUS-treated cells started to increase at days 3 and 7, respectively, and peaked at day 11. LIPUS treatment significantly augmented the production of osteocalcin after day 5. LIPUS caused a significant increase in the mRNA expression of Runx2 and integrin β1, while a significant decline when the integrinβ1 inhibitor was used. Moreover, ALP activity, osteocalcin production as well as calcium nodules of cells treated with both daily LIPUS stimulation and integrinβ1 antibody were less than those in the LIPUS-treated group. In conclusion, LIPUS promotes osteogenic differentiation of hPDLCs, which is associated with upregulation of Runx2 and integrin β1, which may thus provide therapeutic benefits in periodontal tissue regeneration.

Ameliorative effect of bone marrow-derived stem cells on injured liver of mice infected with Schistosoma mansoni

The technique of stem cells or hepatocytes transplantation has recently improved in order to bridge the time before whole-organ liver transplantation. In the present study, unfractionated bone marrow stem cells (BMSCs) were harvested from the tibial and femoral marrow compartments of male mice, which were cultured in Dulbecco's modified Eagle's medium (DMEM) with and without hepatocyte growth factor (HGF), and then transplanted into Schistosoma mansoni-infected female mice on their 8th week post-infection. Mice were sacrificed monthly until the third month of bone marrow transplantation, serum was collected, and albumin concentration, ALT, AST, and alkaline phosphatase (ALP) activities were assayed. On the other hand, immunohistopathological and immunohistochemical changes of granuloma size and number, collagen content, and cells expressing OV-6 were detected for identification of liver fibrosis. BMSCs were shown to differentiate into hepatocyte-like cells. Serum ALT, AST, and ALP were markedly reduced in the group of mice treated with BMSCs than in the untreated control group. Also, granuloma showed a marked decrease in size and number as compared to the BMSCs untreated group. Collagen content showed marked decrease after the third month of treatment with BMSCs. On the other hand, the expression of OV-6 increased detecting the presence of newly formed hepatocytes after BMSCs treatment. BMSCs with or without HGF infusion significantly enhanced hepatic regeneration in S. mansoni-induced fibrotic liver model and have pathologic and immunohistopathologic therapeutic effects. Also, this new therapeutic trend could generate new hepatocytes to improve the overall liver functions.

Induction of human embryonic and induced pluripotent stem cells into urothelium

In vitro generation of human urothelium from stem cells would be a major advancement in the regenerative medicine field, providing alternate nonurologic and/or nonautologous tissue sources for bladder grafts. Such a model would also help decipher the mechanisms of urothelial differentiation and would facilitate investigation of deviated differentiation of normal progenitors into urothelial cancer stem cells, perhaps elucidating areas of intervention for improved treatments. Thus far, in vitro derivation of urothelium from human embryonic stem cells (hESCs) or human induced pluripotent stem (hiPS) cells has not been reported. The goal of this work was to develop an efficient in vitro protocol for the induction of hESCs into urothelium through an intermediary definitive endoderm step and free of matrices and cell contact. During directed differentiation in a urothelial-specific medium ("Uromedium"), hESCs produced up to 60% urothelium, as determined by uroplakin expression; subsequent propagation selected for 90% urothelium. Alteration of the epithelial and mesenchymal cell signaling contribution through noncell contact coculture or conditioned media did not enhance the production of urothelium. Temporospatial evaluation of transcription factors known to be involved in urothelial specification showed association of IRF1, GET1, and GATA4 with uroplakin expression. Additional hESC and hiPS cell lines could also be induced into urothelium using this in vitro system. These results demonstrate that derivation and propagation of urothelium from hESCs and hiPS cells can be efficiently accomplished in vitro in the absence of matrices, cell contact, or adult cell signaling and that the induction process appears to mimic normal differentiation.

Isolation of neural progenitor cells from the human adult subventricular zone based on expression of the cell surface marker CD271

Neural progenitor cells (NPCs) in the subventricular zone (SVZ) hold promise for future therapy for neurodegenerative disorders, because the stimulation of adult neurogenesis could potentially restore the function of degenerating neurons and glia. To obtain more knowledge on these NPCs, we developed a method to specifically isolate NPCs from postmortem adult human brains based on the expression of the specific human adult neural stem/progenitor cell marker glial fibrillary acidic protein δ (GFAPδ). An extensive immunophenotyping analysis for cell surface markers resulted in the observation that CD271 was limited to the SVZ-derived GFAPδ-positive cells. CD271(+) cells developed into neurospheres and could be differentiated into astrocytes, neurons, and oligodendrocytes. We are the first to show that a pure population of NPCs can be isolated from the adult human SVZ, which is highly instrumental for developing future therapies based on stimulating endogenous SVZ neurogenesis.

Human adult white matter progenitor cells are multipotent neuroprogenitors similar to adult hippocampal progenitors

Adult neural progenitor cells (aNPC) are a potential autologous cell source for cell replacement in neurologic diseases or for cell-based gene therapy of neurometabolic diseases. Easy accessibility, long-term expandability, and detailed characterization of neural progenitor cell (NPC) properties are important requisites for their future translational/clinical applications. aNPC can be isolated from different regions of the adult human brain, including the accessible subcortical white matter (aNPCWM), but systematic studies comparing long-term expanded aNPCWM with aNPC from neurogenic brain regions are not available. Freshly isolated cells from subcortical white matter and hippocampus expressed oligodendrocyte progenitor cell markers such as A2B5, neuron-glial antigen 2 (NG2), and oligodendrocyte transcription factor 2 (OLIG2) in ∼20% of cells but no neural stem cell (NSC) markers such as CD133 (Prominin1), Nestin, SOX2, or PAX6. The epidermal growth factor receptor protein was expressed in 18% of aNPCWM and 7% of hippocampal aNPC (aNPCHIP), but only a small fraction of cells, 1 of 694 cells from white matter and 1 of 1,331 hippocampal cells, was able to generate neurospheres. Studies comparing subcortical aNPCWM with their hippocampal counterparts showed that both NPC types expressed mainly markers of glial origin such as NG2, A2B5, and OLIG2, and the NSC/NPC marker Nestin, but no pericyte markers. Both NPC types were able to produce neurons, astrocytes, and oligodendrocytes in amounts comparable to fetal NSC. Whole transcriptome analyses confirmed the strong similarity of aNPCWM to aNPCHIP. Our data show that aNPCWM are multipotent NPC with long-term expandability similar to NPC from hippocampus, making them a more easily accessible source for possible autologous NPC-based treatment strategies.

Chemically induced specification of retinal ganglion cells from human embryonic and induced pluripotent stem cells

The loss of retinal ganglion cells (RGCs) is the primary pathological change for many retinal degenerative diseases. Although there is currently no effective treatment for this group of diseases, cell transplantation to replace lost RGCs holds great potential. However, for the development of cell replacement therapy, better understanding of the molecular details involved in differentiating stem cells into RGCs is essential. In this study, a novel, stepwise chemical protocol is described for the differentiation of human embryonic stem cells and induced pluripotent stem cells into functional RGCs. Briefly, stem cells were differentiated into neural rosettes, which were then cultured with the Notch inhibitor N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT). The expression of neural and RGC markers (BRN3A, BRN3B, ATOH7/Math5, γ-synuclein, Islet-1, and THY-1) was examined. Approximately 30% of the cell population obtained expressed the neuronal marker TUJ1 as well the RGC markers. Moreover, the differentiated RGCs generated action potentials and exhibited both spontaneous and evoked excitatory postsynaptic currents, indicating that functional and mature RGCs were generated. In combination, these data demonstrate that a single chemical (DAPT) can induce PAX6/RX-positive stem cells to undergo differentiation into functional RGCs.