Stem Cell

In mammals, the skin comprises several distinct cell populations that are organized into the following layers: epidermis (stratum corneum, stratum granulosum, stratum spinosum, and basal layer), basement membrane, dermis, and hypodermal (subcutaneous fat) layers. It is vital to identify the exact location and function of proteins in different skin layers. Laser capture microdissection (LCM) is an effective technique for obtaining pure cell populations from complex tissue sections for disease-specific genomic and proteomic analysis. In this study, we used LCM to isolate different skin layers, constructed a stratified developmental lineage proteome map of human skin that incorporates spatial protein distribution, and obtained new insights into the role of extracellular matrix (ECM) on stem cell regulation.

Bioluminescence imaging (BLI) technology is an advanced method of carrying out molecular imaging on live laboratory animals in vivo. This powerful technique is widely-used in studying a variety of biological processes, and it has been an ideal tool in exploring tumor growth and metastatic spread in real-time. This technique ensures the optimal use of laboratory animal resources, particularly the ethical principle of reduction in animal use, given its non-invasive nature, ensuring that ongoing biological processes can be studied over time in the same animal, without the need to euthanize groups of mice at specific time points. In this protocol, the luciferase imaging technique was developed to study the effect of co-inoculating pericytes (contractile, αSMA⁺ mesenchymal stem cell-like cells, located abluminally in microvessels) on the growth and metastatic spread of ovarian cancers using an aggressive ovarian cancer cell line–OVCAR-5–as an example.

Airway basal stem cells are the progenitor cells within the airway that exhibit the capacity to self-renew and give rise to multiple types of differentiated airway epithelial cells. This stem cell-derived epithelium displays organized architecture with functional attributes of the airway mucosa. A protocol has been developed to culture and expand human airway basal stem cells while preserving their stem cell properties and capacity for subsequent mucociliary differentiation. This achievement presents a previously unrealized opportunity to maintain a durable supply of progenitor cells derived from healthy donors to differentiate into human primary airway epithelium for cellular and molecular-based studies. Further, basal stem cells can be harvested from patients with a specific airway disease, such as cystic fibrosis, enabling investigation of potentially altered behavior of disease-specific cells in the appropriate context of the airway mucosa. Here we describe, in detail, a protocol for the serial expansion of airway basal stem cells to enable the generation of nearly unlimited airway basal cells that can be stored and readily available for subsequent culturing and differentiation. In addition, we describe culturing and differentiation of airway basal stem cells on permeable transwell filters at air-liquid interface to create functional mucociliary pseudostratified polarized airway epithelial mucosa.

Stem cells are widely used for numerous clinical applications including limbal stem cell deficiency. Stem cell derived from the bulge region of the hair follicle have the ability to differentiate into a variety of cell types including interfollicular epidermis, hair follicle structures, sebaceous glands and corneal epithelial cells when provided the appropriate cues. Hair follicle stem cells are being studied as a valuable source of autologous stem cells to treat disease. The protocol described below details the isolation and expansion of these cells for eventual clinical application. We used a dual-reporter mouse model to visualize both isolation and eventual differentiation of these cells in a limbal stem cell-deficient mouse model.

The goal of this protocol is to establish a procedure for cultivating stem cells on a fibrin carrier to allow for eventual transplantation to the eye. The ability to transfer stem cells to a patient is critical for treatment for a variety of disorders and wound repair. We took hair follicle stem cells from the vibrissae of transgenic mice expressing a dual reporter gene under the control of the Tet-on system and the keratin 12 promoter (Meyer-Blazejewska et al., 2011). A clonal growth assay was performed to enrich for stem cells. Once holoclones formed they were transferred onto a fibrin carrier and cultivated to obtain a confluent epithelial cell layer. Limbal stem cell deficient (LSCD) mice were used as the transplant recipient in order to test for successful grafting and eventual differentiation into a corneal epithelial phenotype.

Circulating endothelial progenitor cells (EPCs) have been the focus of many clinical trials due to their roles in revascularisation following ischemic events such as acute myocardial infarction as well as their contribution to vascular repair during organ transplantation. Research on EPCs has been controversial due to the lack of distinct markers expressed at the cell surface and varying methods for isolation and culture have resulted in the identification of a multitude of cell types, with differing phenotype and function, all falling under the label of “EPCs”. The most widely documented EPCs isolated for cell therapy are adherent in nature and lacking the progenitor markers such as CD133 and therefore unlikely to represent a true circulating EPC, the cells mobilised in response to a vascular injury.

We recently published the isolation and extensive characterisation of a population of non-adherent endothelial forming cells (naEFCs) (Appleby et al., 2012) (Figure 1). These cells expressed the progenitor cell markers (CD133, CD34, CD117, CD90 and CD38) together with mature endothelial cell markers (VEGFR2, CD144 and CD31). These cells also expressed low levels of CD45 but did not express the lymphoid markers (CD3, CD4, CD8) or myeloid markers (CD11b and CD14) which distinguishes them from ‘early’ EPCs, the ‘late outgrowth EPC’ [more recently known as endothelial colony forming cells (ECFCs)] as well as mature endothelial cells (ECs). Figure 2A exemplifies the surface expression profile of the naEFCs. Functional studies demonstrated that these naEFCs (i) bound Ulex europaeus lectin (Figure 2A), (ii) demonstrated acetylated-low density lipoprotein uptake, (iii) increased vascular cell adhesion molecule (VCAM-1) surface expression in response to tumor necrosis factor and (iv) in co-culture with mature ECs increased the number of tubes, tubule branching and loops in a 3-dimensional in vitro matrix. More importantly, naEFCs placed in vivo generated new lumen containing vasculature lined by CD144 expressing human ECs and have contributed to various advances in scientific knowledge (Appleby et al., 2012; Barrett et al., 2011; Moldenhauer et al., 2015; Parham et al., 2015). Here, we describe the isolation and enrichment of a non-adherent CD133⁺ endothelial forming population of cells from human cord blood.

The intestine, together with skin and blood, belongs to the organs with the highest cell turnover, which makes it a perfect model to study cellular processes, such as proliferation and differentiation. Epithelial cell turnover in intestine is possible due to the presence of intestinal stem cells, which are located at the bottom of the crypt. Here, we recapitulate a detailed protocol for the isolation and culture procedures of primary epithelial intestinal cells in a three - dimensional (3D) in vitro system, described for the first time by Hans Clevers group (Sato et al., 2009). This specific 3D culture preserves intestinal stem cells, which give rise to differentiated progeny for example goblet cells. The culture has many applications and represents a useful model to study stem cell biology, epithelial cell regeneration, and transplantation studies. Moreover, the presented 3D culture can be used to investigate the barrier function of intestinal epithelial cells, as well as heterotypic cell interactions between epithelial cells and stromal cells.