Re: Selection of Stem Cells by Using Antibodies That Target Different CD34 Epitopes Yields Different Patterns of T-Cell Differentiation

Identification, isolation, characterization, and banking of human dental pulp stem cells

Dental pulp stem cells (DPSCs) can be found within the "cell rich zone" of the dental pulp. Their embryonic origin, from neural crests, explains their multipotency. Up to now, it has been demonstrated that these cells are capable of producing bone tissue, both in vitro and in vivo, as well as a simil-dentin tissue, in vitro. In addition, it has been reported that these cells differentiate into adipocytes, endotheliocytes, melanocytes, neurons, and glial cells and can be easily cryopreserved and stored for long periods of time and retain their multipotency and bone-producing capacity. Moreover, recent attention has been focused on tissue engineering and on the properties of these cells: several scaffolds have been used to promote 3D tissue formation and studies have demonstrated that DPSCs show good adherence and bone tissue formation on microconcavity surface textures. In addition, adult bone tissue with good vascularization has been obtained in grafts. Interestingly, they seem to possess immunoprivileges as they can be grafted into allogenic tissues and seem to exert anti-inflammatory abilities, like many other mesenchymal stem cells. Their recent use in clinical trials for bone repair enforces the notion that DPSCs can be used successfully in patients. Therefore, their isolation, selection, differentiation, and banking are of great importance. The isolation technique used in most laboratories is based on the use of flow cytometry with cell sorter termed FACS (fluorescent activated cell sorter). It is now important to obtain new methods/protocols to select and isolate stem cells without staining by fluorescent markers or use of magnetic beads. These new procedures should be based on biophysical differences among the different cell populations in order to obtain interesting peculiarities for implementation in biomedical/clinical laboratories. It is emphasized that the new methods must address simplicity and short times of preparation and use of samples, complete sterility of cells, the potential disposable, low cost and complete maintenance of the viability, and integrity of the cells with real-time response for subsequent applications in the biomedical/clinical/surgical fields.

Progenitor stem cell marker expression by pulmonary carcinomas

Carcinomas may arise as a disorder of regeneration, so that a malignant cell may represent a failure to fully attain the characteristics of differentiated tissue. We hypothesized that there is a differential distribution of progenitor cell markers among different histological types of lung cancers, with poorly differentiated tumors being more likely to express progenitor stem cell markers. The study was limited to paraffin-embedded archival material of resected untreated pulmonary carcinomas, including adenocarcinoma, squamous cell carcinoma, large cell carcinoma, and small cell carcinoma. The sections were stained for putative stem cells markers (Musashi-1, Musashi-2, CD34, CD21, KIT, CD133, p63, and OCT-4). Positivity was read as isolated, focal, or diffuse staining. Stem cell markers were detected in all histological types of pulmonary carcinomas. There was a difference in the expression of markers among the histological types. Small cell carcinoma showed diffuse positivity for most of the markers; in contrast to focal or negative staining in other histological groups. An inverse relationship between CD21 and Musashi-1 was observed. No staining for OCT-4 and CD34 was seen in any of the tumor types. Hierarchical clustering based on marker expression separated tumors into two groups, with one group marked by high expression of Musashi-1 and KIT, contained most of the poorly differentiated adenocarcinomas and small cell carcinomas. Therefore, stem cell markers are expressed in lung cancers with different patterns seen for different histological types and degrees of differentiation.

Advances in complex multiparameter flow cytometry technology: Applications in stem cell research

Flow cytometry and cell sorting are critical tools in stem cell research. Recent advances in flow cytometric hardware, reagents, and software have synergized to permit the stem cell biologist to more fully identify and isolate rare cells based on their immunofluorescent and light scatter characteristics. Some of these improvements include physically smaller air-cooled lasers, new designs in optics, new fluorescent conjugate-excitation pairs, and improved software to visualize data, all which combine to open up new horizons in the study of stem cells, by enhancing the resolution and specificity of inquiry. In this review, these recent improvements in technology will be outlined and important cell surface and functional antigenic markers useful for the study of stem cells described.