Primate embryonic stem cells create their own niche while differentiating in three-dimensional culture systems

Human Amniotic Epithelial Cells Promote the Proliferation of Human Corneal Endothelial Cells by Regulating Telomerase Activity via the Wnt/β-catenin Pathway

PURPOSE

Human amniotic epithelial cells (HAECs) have regenerative properties and low immunogenicity, which have enabled their use without immune rejection in regenerative medicine applications, such as wound repair, corneal surgery and burn repair. The aim of this study was to explore the potential role of HAECs in the proliferation of human corneal endothelial cells (HCEnCs) and the possible mechanism of regulation.

METHODS

HAECs and HCEnCs were isolated from donated tissue samples and were cultured; the collected HAEC culture medium (HAEC-Me) was added to the human corneal endothelium medium (CEM) to establish the HAEC-CM system. HCEnCs were cultured in CEM, 20%HAEC-Me, 20% HAEC-CM, 20% HAEC-CM supplemented with a GSK-3β inhibitor TWS119 or CEM supplemented with TWS119. Then, cell proliferation, apoptosis, cell cycle progression, telomerase activity, and Wnt/β-catenin pathway-related protein levels were assessed.

RESULTS

We found that the HCEnCs cultured in the 20% HAEC-CM had increased proliferative capacity, telomerase activity and β-catenin and Tcf4 expression levels, and they had a decrease in the rate of apoptosis and α-SMA expression when they were compared with the HCEnCs cultured in the 20% HAEC-Me. After GSK-3β was inhibited by TWS119, HCEnCs cultured in CEM or 20% HAEC-CM had an increased proliferative capacity, telomerase activity, β-catenin/Tcf4 expression and a decreased α-SMA expression, and they had a decreased apoptotic rate.

CONCLUSIONS

These data indicate that the human amniotic epithelial cells microenvironment can promote the proliferation of human corneal endothelial cells, which may be related to regulating telomerase activity and epithelial-to-mesenchymal transition (EMT) via the Wnt/β-catenin pathway.

Inhibition of Pseudomonas aeruginosa biofilm formation by 2,2'-bipyridyl, lipoic, kojic and picolinic acids

OBJECTIVES

The inhibitory effects of iron chelators, and FeCl3 chelation on biofilm formation and swarming motility were investigated against an opportunistic human pathogen Pseudomonas aeruginosa.

MATERIALS AND METHODS

The inhibitory activity of 2,2'-bipyridyl, lipoic acid, kojic acid and picolinic acid on biofilm formation of P. aeruginosa strain PAO1 and three clinical isolates (P. aeruginosa PAK01, P. aeruginosa PAK02 and P. aeruginosa PAK03) were investigated, based on crystal violet assay, and swarming motility test.

RESULTS

The kojic, lipoic and picolinic acid inhibited biofilm formation by 5-33% in all tested P. aeruginosa isolates. When chelated iron was added, biofilm inhibition rates were determined to be 39-57%. Among the tested chelators against P. aeruginosa, lipoic acid (84%) and kojic acid (68%) presented the highest inhibition of swarming motility. This is the first study to report the inhibitory effect of lipoic acid on biofilm formation and swarming motility of P. aeruginosa.

CONCLUSION

It is considered that lipoic and picolinic acids can serve as alternatives for the treatment of the P. aeruginosa infections by inhibiting biofilm formation.

Decellularized kidney in the presence of chondroitin sulfate as a natural 3D scaffold for stem cells

OBJECTIVES

Use of biological scaffolds and automating the cells directing process with materials such as growth factors and glycosaminoglycans (GAGs) in a certain path may have beneficial effects in tissue engineering and regenerative medicine in future. In this research, chondroitin sulfate sodium was used for impregnation of the scaffolds. It is a critical component in extracellular matrix and plays an important role in signaling pathway; however, little is known about its role within mammalian development and cell linage specification.

MATERIALS AND METHODS

Due to its porous and appropriate structure and for putting cells in 3D space, the kidney of BALB/c mouse was selected and decellulalized using physical and chemical methods. After decellularization, the scaffold was impregnated in chondroitin sulfate solution (CS) for 24 hr. Then, 60×10(5) human adipose-derived mesenchymal stem cells were seeded on the scaffold to assess their behavior on day 5, 10, 15, 20, and 25.

RESULTS

After 48 hr, DAPI staining approved completed decellularized kidney by 1% SDS (sodium dodecyl sulfate). Migration and establishment of a number of cells to the remaining area of the glomerulus was observed. In addition, cell accumulation on the scaffold surface as well as cells migration to the depth of kidney formed an epithelium-like structure. Up to the day 15, microscopic study of different days of seeding showed the gradual adhesion of large number of cells to the scaffold.

CONCLUSION

Glycosaminoglycan could be a right option for impregnation. It is used for smartification and strengthening of natural scaffolds and induction of some behaviors in stem cells.

The regulation of growth and metabolism of kidney stem cells with regional specificity using extracellular matrix derived from kidney

Native extracellular matrix (ECM) that is secreted and maintained by resident cells is of great interest for cell culture and cell delivery. We hypothesized that specialized bioengineered niches for stem cells can be established using ECM-derived scaffolding materials. Kidney was selected as a model system because of the high regional diversification of renal tissue matrix. By preparing the ECM from three specialized regions of the kidney (cortex, medulla, and papilla; whole kidney, heart, and bladder as controls) in three forms: (i) intact sheets of decellularized ECM, (ii) ECM hydrogels, and (iii) solubilized ECM, we investigated how the structure and composition of ECM affect the function of kidney stem cells (with mesenchymal stem cells, MSCs, as controls). All three forms of the ECM regulated KSC function, with differential structural and compositional effects. KSCs cultured on papilla ECM consistently displayed lower proliferation, higher metabolic activity, and differences in cell morphology, alignment, and structure formation as compared to KSCs on cortex and medulla ECM, effects not observed in corresponding MSC cultures. These data suggest that tissue- and region-specific ECM can provide an effective substrate for in vitro studies of therapeutic stem cells.

Gene expression signatures of extracellular matrix and growth factors during embryonic stem cell differentiation

Pluripotent stem cells are uniquely capable of differentiating into somatic cell derivatives of all three germ lineages, therefore holding tremendous promise for developmental biology studies and regenerative medicine therapies. Although temporal patterns of phenotypic gene expression have been relatively well characterized during the course of differentiation, coincident patterns of endogenous extracellular matrix (ECM) and growth factor expression that accompany pluripotent stem cell differentiation remain much less well-defined. Thus, the objective of this study was to examine the global dynamic profiles of ECM and growth factor genes associated with early stages of pluripotent mouse embryonic stem cell (ESC) differentiation. Gene expression analysis of ECM and growth factors by ESCs differentiating as embryoid bodies for up to 14 days was assessed using PCR arrays (172 unique genes total), and the results were examined using a variety of data mining methods. As expected, decreases in the expression of genes regulating pluripotent stem cell fate preceded subsequent increases in morphogen expression associated with differentiation. Pathway analysis generated solely from ECM and growth factor gene expression highlighted morphogenic cell processes within the embryoid bodies, such as cell growth, migration, and intercellular signaling, that are required for primitive tissue and organ developmental events. In addition, systems analysis of ECM and growth factor gene expression alone identified intracellular molecules and signaling pathways involved in the progression of pluripotent stem cell differentiation that were not contained within the array data set. Overall, these studies represent a novel framework to dissect the complex, dynamic nature of the extracellular biochemical milieu of stem cell microenvironments that regulate pluripotent cell fate decisions and morphogenesis.

Cancer Tissue Engineering: A Novel 3D Polystyrene Scaffold for In Vitro Isolation and Amplification of Lymphoma Cancer Cells from Heterogeneous Cell Mixtures

Isolation and amplification of primary lymphoma cells in vitro setting is technically and biologically challenging task. To optimize culture environment and mimic in vivo conditions, lymphoma cell lines were used as a test case and were grown in 3-dimension (3D) using a novel 3D tissue culture polystyrene scaffold with neonatal stromal cells to represent a lymphoma microenvironment. In this model, the cell proliferation was enhanced more than 200-fold or 20,000% neoplastic surplus in 7 days when less than 1% lymphoma cells were cocultured with 100-fold excess of neonatal stroma cells, representing 3.2-fold higher proliferative rate than 2D coculture model. The lymphoma cells grew and aggregated to form clusters during 3D coculture and did not maintained the parental phenotype to grow in single-cell suspension. The cluster size was over 5-fold bigger in the 3D coculture by day 4 than 2D coculture system and contained less than 0.00001% of neonatal fibroblast trace. This preliminary data indicate that novel 3D scaffold geometry and coculturing environment can be customized to amplify primary cancer cells from blood or tissues related to hematological cancer and subsequently used for personalized drug screening procedures.

Human cord blood CD133+ stem cells transplanted to nod-scid mice provide conditions for regeneration of olfactory neuroepithelium after permanent damage induced by dichlobenil

The herbicide dichlobenil selectively causes necrosis of the dorsomedial part of olfactory neuroepithelium (NE) with permanent damage to the underlying mucosa, whereas the lateral part of the olfactory region and the nasal respiratory mucosa remain undamaged. We investigated here whether human umbilical cord blood CD133(+) stem cells (HSC) injected intravenously to nod-scid mice pretreated with dichlobenil may engraft the olfactory mucosa and contribute to the regeneration of the damaged NE. We tested HLA-DQalpha1 DNA and three human microsatellites (Combined DNA Index System) as indicators of engrafted cells, finding polymerase chain reaction evidence of chimaerism in various tissues of the host, including the olfactory mucosa and bulb, at 7 and 31 days following HSC transplantation. Histology, immunohistochemistry, and lectin staining revealed the morphological recovery of the dorsomedial region of the NE in dichlobenil-treated mice that received HSC, contrasting with the lack of regeneration in similarly injured areas as these remained damaged in control nontransplanted mice. FISH analysis, to detect human genomic sequences from different chromosomes, confirmed persistent engraftment of the regenerating olfactory area with chimeric cells. Electro-olfactograms in response to odorants, to test the functionality of the olfactory NE, confirmed the functional damage of the dorsomedial area in dichlobenil-treated mice and the functional recovery of the same area in transplanted mice. These findings support the concept that transplanted HSC migrating to the damaged olfactory area provide conditions facilitating the recovery from olfactory receptor cell loss.

"The good into the pot, the bad into the crop!"--a new technology to free stem cells from feeder cells

A variety of embryonic and adult stem cell lines require an initial co-culturing with feeder cells for non-differentiated growth, self renewal and maintenance of pluripotency. However for many downstream ES cell applications the feeder cells have to be considered contaminations that might interfere not just with the analysis of experimental data but also with clinical application and tissue engineering approaches. Here we introduce a novel technique that allows for the selection of pure feeder-freed stem cells, following stem cell proliferation on feeder cell layers. Complete and reproducible separation of feeder and embryonic stem cells was accomplished by adaptation of an automated cell selection system that resulted in the aspiration of distinct cell colonies or fraction of colonies according to predefined physical parameters. Analyzing neuronal differentiation we demonstrated feeder-freed stem cells to exhibit differentiation potentials comparable to embryonic stem cells differentiated under standard conditions. However, embryoid body growth as well as differentiation of stem cells into cardiomyocytes was significantly enhanced in feeder-freed cells, indicating a feeder cell dependent modulation of lineage differentiation during early embryoid body development. These findings underline the necessity to separate stem and feeder cells before the initiation of in vitro differentiation. The complete separation of stem and feeder cells by this new technology results in pure stem cell populations for translational approaches. Furthermore, a more detailed analysis of the effect of feeder cells on stem cell differentiation is now possible, that might facilitate the identification and development of new optimized human or genetically modified feeder cell lines.

Cochlear Repair by Transplantation of Human Cord Blood CD133+ Cells to Nod-Scid Mice Made Deaf with Kanamycin and Noise

We investigated the fate of human cord blood CD133+ hematopoietic stem cells (HSC) transplanted intravenously (IV) into irradiated nodscid mice previously made deaf by ototoxic treatment with kanamycin and/or intense noise, to verify whether HSC engraft the cochlea and contribute to inner ear restoration, in vivo. We tested the presence of HLA.DQα1 by PCR, used for traceability of engrafted cells, finding evidence that HSC migrated to various host tissues, including the organ of Corti (OC). By histology, antibody and lectin-staining analysis, we confirmed that HSC IV transplantation in mice previously damaged by ototoxic agents correlated with the repair process and stimulation ex novo of morphological recovery in the inner ear, while the cochlea of control oto-injured, nontransplanted mice remained seriously damaged. Dual color FISH analysis also provided evidence of positive engraftment in the inner ear and in various mouse tissues, also revealing small numbers of heterokaryons, probably derived from fusion of donor with endogenous cells, for up to 2 months following transplantation. These observations offer the first evidence that transplanted human HSC migrating to the inner ear of oto-injured mice may provide conditions for the resumption of deafened cochlea, emerging as a potential strategy for inner ear rehabilitation.