Angiogenic property of silk fibroin scaffolds with adipose-derived stem cells on chick chorioallantoic membrane.

Angiogenesis is a crucial step in tissue regeneration and repair. Biomaterials that allow or promote angiogenesis are thus beneficial. In this study, angiogenic properties of salt-leached silk fibroin (SF) scaffolds seeded with human adipose stem cells (hADSCs) were studied using chick chorioallantoic membrane (CAM) as a model. The hADSC-seeded SF scaffolds (SF-hADSC) with the porosity of 77.34 ± 6.96% and the pore diameter of 513.95 ± 4.99 µm were implanted on the CAM of chick embryos that were on an embryonic day 8 (E8) of development. The SF-hADSC scaffolds induced a spoke-wheel pattern of capillary network indicative of angiogenesis, which was evident since E11. Moreover, the ingrowth of blood vessels into the scaffolds was seen in histological sections. The unseeded scaffolds induced the same extent of angiogenesis later on E14. By contrast, the control group could not induce the same extent of angiogenesis. In vitro cytotoxicity tests and in vivo angioirritative study reaffirmed the biocompatibility of the scaffolds. This work highlighted that the biocompatible SF-hADSC scaffolds accelerate angiogenesis, and hence they can be a promising biomaterial for the regeneration of tissues that require angiogenesis.

The Effect of Okra (Abelmoschus esculentus (L.) Moench) Seed Extract on Human Cancer Cell Lines Delivered in Its Native Form and Loaded in Polymeric Micelles.

Cancer is a noncommunicable disease with a high worldwide incidence and mortality rate. The National Cancer Institute of Thailand reports increasing cumulative incidence of breast, colorectal, liver, lung, and cervical cancers, accounting for more than 60% of all cancers in the kingdom. In this current work, we attempt to elucidate the phytochemical composition of the okra (Abelmoschus esculentus (L.) Moench) seed extract (OSE) and study its anticancer activity, delivered in its native form as well as in the form of polymeric micelles with enhanced solubility, in three carcinoma cell lines (MCF-7, HeLa, and HepG2). The presence of flavonoid compounds in the OSE was successfully confirmed, and direct delivery had the highest cytotoxic effect on the breast cancer cell line (MCF-7), followed by the hepatocellular carcinoma (HepG2) and cervical carcinoma (HeLa) cell lines in that order, while its delivery in polymeric micelles further increased this effect only in the HepG2 cell line. The OSE's observed cytotoxic effects on cancer cell lines demonstrated a dose and time-dependent cell proliferation and migration inhibition plausibly due to VEGF production inhibition, leading to apoptosis and cell death, conceivably due to the four flavonoid compounds noted in the current study, one of which was isoquercitrin. However, in view of the latter compound's isolated effects being inferior to those observed by the OSE, we hypothesize that either isoquercitrin requires the biological synergy of any one or all of the observed flavonoids or any of the three in isolation or all in concert are responsible. Further studies are required to elucidate the nature of the three unknown compounds. Furthermore, as we encountered significant problems in dissolving the okra seed extract and creating the polymeric micelles, further studies are needed to devise a clinically beneficial delivery and targeting system.

Emulsion Cross-Linking Technique for Human Fibroblast Encapsulation.

Microencapsulation with biodegradable polymers has potential application in drug and cell delivery systems and is currently used in probiotic delivery. In the present study, microcapsules of human fibroblast cells (CRL2522) were prepared by emulsion cross-linking technique. Tween 80 surfactant at a 2% concentration through phase inversion resulted in the most efficient and stable size, morphology, and the cells survival at least 50% on day 14. Emulsion cross-linking microcapsule preparation resulted in smaller and possibly more diverse particles that can be developed clinically to deliver encapsulated mammalian cells for future disease treatments.

The neural milieu of the developing choroid plexus: neural stem cells, neurons and innervation.

The choroid plexus produces cerebrospinal fluid and plays an important role in brain homeostasis both pre and postnatally. In vitro studies have suggested that cells from adult choroid plexus have stem/progenitor cell-like properties. Our initial aim was to investigate whether such a cell population is present in vivo during development of the choroid plexus, focusing mainly on the chick choroid plexus. Cells expressing neural markers were indeed present in the choroid plexus of chick and also those of rodent and human embryos, both within their epithelium and mesenchyme. ß3-tubulin-positive cells with neuronal morphology could be detected as early as at E8 in chick choroid plexus and their morphological complexity increased with development. Whole mount immunochemistry demonstrated the presence of neurons throughout choroid plexus development and they appeared to be mainly catecholaminergic, as indicated by tyrosine-hydroxylase reactivity. The presence of cells co-labeling for BrdU and the neuroblast marker, doublecortin, in organotypic choroid plexus cultures supported the hypothesis that neurogenesis can occur from neural precursors within the developing choroid plexus. Furthermore, we found that extrinsic innervation is present in the developing choroid plexus, unlike previously suggested. Altogether, our data are consistent with the presence of neural progenitors within the choroid plexus, suggest that at least some of the choroid plexus neurons are born locally, and show for the first time that choroid plexus innervation occurs prenatally. Hence, we propose the existence of a complex neural regulatory network within the developing choroid plexus that may play a crucial role in modulating its function during development as well as throughout life.

High plasticity of pediatric adipose tissue-derived stem cells: too much for selective skeletogenic differentiation?

Stem cells derived from adipose tissue are a potentially important source for autologous cell therapy and disease modeling, given fat tissue accessibility and abundance. Critical to developing standard protocols for therapeutic use is a thorough understanding of their potential, and whether this is consistent among individuals, hence, could be generally inferred. Such information is still lacking, particularly in children. To address these issues, we have used different methods to establish stem cells from adipose tissue (adipose-derived stem cells [ADSCs], adipose explant dedifferentiated stem cells [AEDSCs]) from several pediatric patients and investigated their phenotype and differentiation potential using monolayer and micromass cultures. We have also addressed the overlooked issue of selective induction of cartilage differentiation. ADSCs/AEDSCs from different patients showed a remarkably similar behavior. Pluripotency markers were detected in these cells, consistent with ease of reprogramming to induced pluripotent stem cells. Significantly, most ADSCs expressed markers of tissue-specific commitment/differentiation, including skeletogenic and neural markers, while maintaining a proliferative, undifferentiated morphology. Exposure to chondrogenic, osteogenic, adipogenic, or neurogenic conditions resulted in morphological differentiation and tissue-specific marker upregulation. These findings suggest that the ADSC "lineage-mixed" phenotype underlies their significant plasticity, which is much higher than that of chondroblasts we studied in parallel. Finally, whereas selective ADSC osteogenic differentiation was observed, chondrogenic induction always resulted in both cartilage and bone formation when a commercial chondrogenic medium was used; however, chondrogenic induction with a transforming growth factor ß1-containing medium selectively resulted in cartilage formation. This clearly indicates that careful simultaneous assessment of bone and cartilage differentiation is essential when bioengineering stem cell-derived cartilage for clinical intervention.

Autologous stem cells for personalised medicine.

Increasing understanding of stem cell biology, the ability to reprogramme differentiated cells to a pluripotent state and evidence of multipotency in certain adult somatic stem cells has opened the door to exciting therapeutic advances as well as a great deal of regulatory and ethical issues. Benefits will come from the possibility of modelling human diseases and develop individualised therapies, and from their use in transplantation and bioengineering. The use of autologous stem cells is highly desirable, as it avoids the problem of tissue rejection, and also reduces ethical and regulatory issues. Identification of the most appropriate cell sources for different potential applications, development of appropriate clinical grade methodologies and large scale well controlled clinical trials will be essential to assess safety and value of cell based therapies, which have been generating much hope, but are by and large not yet close to becoming standard clinical practice. We briefly discuss stem cells in the context of tissue repair and regenerative medicine, with a focus on individualised clinical approaches, and give examples of sources of autologous cells with potential for clinical intervention.

Amniotic fluid stem cells increase embryo survival following injury.

Although amniotic fluid cells can differentiate into several mesenchymal lineages and have been proposed as a valuable therapeutic cell source, their ability to undergo terminal neuronal differentiation remains a cause of controversy. The aim of this study was to investigate the neuronal differentiation ability of the c-Kit-positive population from GFP-transgenic rat amniotic fluid, amniotic fluid stem (AFS) cells, and to assess how they affected injury response in avian embryos. AFS cells were found to express several neural stem/progenitor cell markers. However, no overt neuronal differentiation was apparent after either treatment with small molecules known to stimulate neuronal differentiation, attempts to differentiate AFS cell-derived embryoid body-like structures, or grafting AFS cells into environments known to support neuronal differentiation (organotypic rat hippocampal cultures, embryonic chick nervous system). Nonetheless, AFS cells significantly reduced hemorrhage and increased survival when grafted at the site of an extensive thoracic crush injury in E2.5 chick embryos. Increased embryo survival was induced neither by desmopressin treatment, which also reduced hemorrhage, nor by grafting other mesenchymal or neural cells, indicating a specific effect of AFS cells. This was found to be mediated by soluble factors in a transwell coculture model. Altogether, this study shows that AFS cells reduce tissue damage and increase survival in injured embryos, providing a potentially valuable tool as therapeutic agents for tissue repair, particularly prenatal/perinatal repair of defects diagnosed during gestation, but this effect is mediated via paracrine mechanisms rather than the ability of AFS cells to fully differentiate into neuronal cells.