De Francesco

Detection and Characterization of CD133 + Cancer Stem Cells in Human Solid Tumours

Background Osteosarcoma is the most common primary tumour of bone. Solid tumours are made of heterogeneous cell populations, which display different goals and roles in tumour economy. A rather small cell subset can hold or acquire stem potentials, gaining aggressiveness and increasing expectancy of recurrence. The CD133 antigen is a pentaspan membrane glycoprotein, which has been proposed as a cancer stem cell marker, since it has been previously demonstrated to be capable of identifying a cancer initiating subpopulation in brain, colon, melanoma and other solid tumours. Therefore, our aim was to observe the possible presence of cells expressing the CD133 antigen within solid tumour cell lines of osteosarcoma and, then, understand their biological characteristics and performances. Methodology and Principal Findings In this study, using SAOS2, MG63 and U2OS, three human sarcoma cell lines isolated from young Caucasian subjects, we were able to identify and characterize, among them, CD133+ cells showing the following features: high proliferation rate, cell cycle detection in a G2\M phase, positivity for Ki-67, and expression of ABCG2 transporters. In addition, at the FACS, we were able to observe the CD133+ cell fraction showing side population profile and forming sphere-clusters in serum-free medium with a high clonogenic efficiency. Conclusions Taken together, our findings lead to the thought that we can assume that we have identified, for the first time, CD133+ cells within osteosarcoma cell lines, showing many features of cancer stem cells. This can be of rather interest in order to design new therapies against the bone cancer.

Cancer stem cells in solid tumors: an overview and new approaches for their isolation and characterization

Primary tumors are responsible for 10% of cancer deaths. In most cases, the main cause of mortality is the formation of metastases. Accumulating evidence suggests that a subpopulation of tumor cells with distinct stem‐like properties is responsible for tumor initiation, invasive growth, and metastasis formation. This population is defined as cancer stem cells (CSCs). Existing therapies have enhanced the length of survival after diagnosis of cancer but have completely failed in terms of recovery. CSCs appear to be resistant to chemotherapy, may remain quiescent for extended periods, and have affinity for hypoxic environments. The CSCs can be identified and isolated by different methodologies, including isolation by CSC‐specific cell surface marker expression, detection of side population phenotype by Hoechst 33342 exclusion, assessment of their ability to grow as floating spheres, and aldehyde dehydrogenase (ALDH) activity assay. None of the methods mentioned are exclusively used to isolate the solid tumor CSCs, highlighting the imperative to delineate more specific markers or to use combinatorial markers and methodologies. This review provides an overview of the main characteristics and approaches used to identify, isolate, and characterize CSCs from solid tumors.—Tirino, V., Desiderio, V., Paino, F., De Rosa, A., Papaccio, F., La Noce, M., Laino, L., De Francesco, F., Papaccio, G. Cancer stem cells in solid tumors: an overview and new approaches for their isolation and characterization. FASEB J. 27, 13–24 (2013). www.fasebj.org

Human CD34 + /CD90 + ASCs Are Capable of Growing as Sphere Clusters, Producing High Levels of VEGF and Forming Capillaries

Background Human adult adipose tissue is an abundant source of mesenchymal stem cells (MSCs). Moreover, it is an easily accessible site producing a considerable amount of stem cells. Methodology/Principal Findings In this study, we have selected and characterized stem cells within the stromal vascular fraction (SVF) of human adult adipose tissue with the aim of understanding their differentiation capabilities and performance. We have found, within the SVF, different cell populations expressing MSC markers – including CD34, CD90, CD29, CD44, CD105, and CD117 – and endothelial-progenitor-cell markers – including CD34, CD90, CD44, and CD54. Interestingly, CD34+/CD90+ cells formed sphere clusters, when placed in non-adherent growth conditions. Moreover, they showed a high proliferative capability, a telomerase activity that was significantly higher than that found in differentiated cells, and contained a fraction of cells displaying the phenotype of a side population. When cultured in adipogenic medium, CD34+/CD90+ quickly differentiated into adipocytes. In addition, they differentiated into endothelial cells (CD31+/VEGF+/Flk-1+) and, when placed in methylcellulose, were capable of forming capillary-like structures producing a high level of VEGF, as substantiated with ELISA tests. Conclusions/Significance Our results demonstrate, for the first time, that CD34+/CD90+ cells of human adipose tissue are capable of forming sphere clusters, when grown in free-floating conditions, and differentiate in endothelial cells that form capillary-like structures in methylcellulose. These cells might be suitable for tissue reconstruction in regenerative medicine, especially when patients need treatments for vascular disease.

Scaffold's Surface Geometry Significantly Affects Human Stem Cell Bone Tissue Engineering

In this study, we have observed dental pulp stem cells (SBP‐DPSCs) performances on different scaffolds, such as PLGA 85:15, hydroxyapatite chips (HA) and titanium. Stem cells were challenged with each engineered surface, either in plane cultures or in a rotating apparatus, for a month. Gingival fibroblasts were used as controls. Results showed that stem cells exerted a different response, depending on the different type of textured surface: in fact, microconcavities significantly affected SBP‐DPSC differentiation into osteoblasts, both temporally and quantitatively, with respect to the other textured surfaces. Actually, stem cells challenged with concave surfaces differentiated quicker and showed nuclear polarity, an index of secretion, cellular activity and matrix formation. Moreover, bone‐specific proteins were significantly expressed and the obtained bone tissue was of significant thickness. Thus, cells cultured on the concave textured surface had better cell‐scaffold interactions and were induced to secrete factors that, due to their autocrine effects, quickly lead to osteodifferentiation, bone tissue formation, and vascularization. The worst cell performance was obtained using convex surfaces, due to the scarce cell proliferation on to the scaffold and the poor matrix secretion. In conclusion, this study stresses that for a suitable and successful bone tissue reconstruction the surface texture is of paramount importance. J. Cell. Physiol. 214:166–172, 2008.

The osteoblastic differentiation of dental pulp stem cells and bone formation on different titanium surface textures.

Bone Tissue Engineering (BTE) and Dental Implantology (DI) require the integration of implanted structures, with well characterized surfaces, in bone. In this work we have challenged acid-etched titanium (AET) and Laser Sintered Titanium (LST) surfaces with either human osteoblasts or stem cells from human dental pulps (DPSCs), to understand their osteointegration and clinical use capability of derived implants. DPSCs and human osteoblasts were challenged with the two titanium surfaces, either in plane cultures or in a roller apparatus within a culture chamber, for hours up to a month. During the cultures cells on the titanium surfaces were examined for histology, protein secretion and gene expression. Results show that a complete osteointegration using human DPSCs has been obtained: these cells were capable to quickly differentiate into osteoblasts and endotheliocytes and, then, able to produce bone tissue along the implant surfaces. Osteoblast differentiation of DPSCs and bone morphogenetic protein production was obtained in a better and quicker way, when challenging stem cells with the LST surfaces. This successful BTE in a comparatively short time gives interesting data suggesting that LST is a promising alternative for clinical use in DI.

Large-scale production of human adipose tissue from stem cells: a new tool for regenerative medicine and tissue banking.

Adipose tissue is an easy, accessible, and abundant source of mesenchymal stem cells (MSCs) for the reconstruction and addition of soft tissue and for restoration of soft-tissue defects associated with trauma, tumor resections, and congenital deformities. A stable source of adipose cells or tissue is needed for autologous grafting. Therefore, the aim of this study was to obtain enough autologous adipose tissue for possible clinical applications. For this purpose, we isolated MSCs (CD34+/CD90+) from human lipoaspirated or resected fat, which differentiated into adipocytes when placed in culture. Human adipose tissue is a paramount source of autologous MSCs were capable of generating a complete adipose tissue in vitro. Differentiated adipocytes expressed a strong positivity for several specific antibodies, including adiponectin and peroxisome proliferator-activated receptor gamma. In addition, fibroblasts (approximately 10% of the whole sorted-cell population) started to secrete an extracellular matrix after 60 days that was strongly positive for type I collagen and fibronectin. After long-term culture (4 months), an adipose tissue with collagenic fibers and vessels was obtained. This tissue was comparable with adult human adipose tissue and therefore may be a criterion standard for future tissue repair and regeneration and for therapeutic and transplantation purposes.

Human Ng2+ adipose stem cells loaded in vivo on a new crosslinked hyaluronic acid-lys scaffold fabricate a skeletal muscle tissue†‡

Mesenchymal stem cell (MSC) therapy holds promise for treating diseases and tissue repair. Regeneration of skeletal muscle tissue that is lost during pathological muscle degeneration or after injuries is sustained by the production of new myofibers. Human Adipose stem cells (ASCs) have been reported to regenerate muscle fibers and reconstitute the pericytic cell pool after myogenic differentiation in vitro. Our aim was to evaluate the differentiation potential of constructs made from a new cross‐linked hyaluronic acid (XHA) scaffold on which different sorted subpopulations of ASCs were loaded. Thirty days after engraftment in mice, we found that NG2+ ASCs underwent a complete myogenic differentiation, fabricating a human skeletal muscle tissue, while NG2− ASCs merely formed a human adipose tissue. Myogenic differentiation was confirmed by the expression of MyoD, MF20, laminin, and lamin A/C by immunofluorescence and/or RT‐PCR. In contrast, adipose differentiation was confirmed by the expression of adiponectin, Glut‐4, and PPAR‐γ. Both tissues formed expressed Class I HLA, confirming their human origin and excluding any contamination by murine cells. In conclusion, our study provides novel evidence that NG2+ ASCs loaded on XHA scaffolds are able to fabricate a human skeletal muscle tissue in vivo without the need of a myogenic pre‐differentiation step in vitro. We emphasize the translational significance of our findings for human skeletal muscle regeneration. J. Cell. Physiol. 228: 1762–1773, 2013.

Human adipose CD34+CD90+ stem cells and collagen scaffold constructs grafted in vivo fabricate loose connective and adipose tissues

Stem cell based therapies for the repair and regeneration of various tissues are of great interest for a high number of diseases. Adult stem cells, instead, are more available, abundant and harvested with minimally invasive procedures. In particular, mesenchymal stem cells (MSCs) are multi‐potent progenitors, able to differentiate into bone, cartilage, and adipose tissues. Human adult adipose tissue seems to be the most abundant source of MSCs and, due to its easy accessibility; it is able to give a considerable amount of stem cells. In this study, we selected MSCs co‐expressing CD34 and CD90 from adipose tissue. This stem cell population displayed higher proliferative capacity than CD34−CD90− cells and was able to differentiate in vitro into adipocytes (PPARγ+ and adiponectin+) and endothelial cells (CD31+VEGF+Flk1+). In addition, in methylcellulose without VEGF, it formed a vascular network. The aim of this study was to investigate differentiation potential of human adipose CD34+/CD90+ stem cells loaded onto commercial collagen sponges already used in clinical practice (Gingistat) both in vitro and in vivo. The results of this study clearly demonstrate that human adult adipose and loose connective tissues can be obtained in vivo, highlighting that CD34+/CD90 ASCs are extremely useful for regenerative medicine. J. Cell. Biochem. 114: 1039–1049, 2013.

Histologic Effects of External Ultrasound-Assisted Lipectomy on Adipose Tissue

This study aimed to observe the effects of ultrasound waves at different frequencies on abdominal fat tissue. External ultrasound-assisted lipectomy (XUAL) via both histologic and immunohistochemic examinations was used to assess adipose tissue alterations, including cells and collagenic fibers. The results, at the immunofluorescence level, show that ultrasound used at 1 MHz with a potency of 3 W resulted in no alterations or only limited cell destruction with collagen fibers intact. In contrast, when the ultrasound was 2 and especially 3 MHz, adipocyte alterations usually were evident. Massive adipose tissue destruction, confirmed using Oil red-O staining, was observed. In addition, at the immunofluorescence level, diffuse collagen fiber retraction was detected. This was particularly evident in comparisons with biopsies of intact control samples, which showed normal adipose tissue and intact collagen fibers. The results obtained using morphologic techniques, which do not allow fixation artifacts and include collagen observations, demonstrate that with the XUAL technique, ultrasound at 1 MHz does not induce cellular alterations. In contrast, both 2- and 3-MHz frequencies are capable of causing complete fat tissue disruption, including destruction of adipose cells and collagenic fibers.

An innovative regenerative treatment of scars with dermal micrografts

Pathological scars occur following injuries and are often considered esthetically unattractive. Several strategies have been attempted to improve these types of scars using both surgical and nonsurgical methods. The most common treatments include cryotherapy, intralesional corticosteroid injections, 5‐fluorouracil, bleomycin, interferon, and verapamil.