Native human adipose stromal cells: localization, morphology and phenotype

Adipose tissue is increasingly recognized as a source of mesenchymal stromal cells for regenerative applications. While cultured adipose-derived stromal cells (ASCs) have been widely studied, native ASCs remain poorly characterized. Established knowledge includes their potential for differentiation and tissue repair. However, the immunophenotype, morphology, and localization of native ASCs within adipose tissue are not well defined. Prior research has shown that bone marrow-derived mesenchymal stromal cells exhibit specific marker profiles and functions. This gap motivated the current investigation into native ASCs to compare them with bone marrow-derived cells. No prior work had resolved the precise immunophenotype of native ASCs in situ. Understanding these features could improve stem cell-based therapies. The lack of detailed morphological and phenotypic data on native ASCs limits their clinical application. This study aimed to address these unresolved questions.

The goal of this work was to investigate the native characteristics of human adipose-derived stromal cells. Researchers sought to determine the immunophenotype, morphology, and localization of these cells within adipose tissue. They also aimed to compare native ASCs with bone marrow-derived mesenchymal stromal cells. The study focused on the stromal vascular fraction of adipose tissue as a source of native ASCs. Immunoselection was used to isolate specific cell subtypes for analysis. Confocal imaging and immunohistochemistry were employed to visualize ASCs in situ. The researchers wanted to clarify whether native ASCs express markers similar to those of bone marrow-derived cells. By examining these features, they hoped to better understand the biological role of ASCs in adipose tissue.

The stromal vascular fraction of human adipose tissue was isolated using enzymatic digestion. Native cell subtypes were separated through immunoselection based on CD34 expression. Immunohistological techniques were used to examine ASCs in tissue samples. Confocal microscopy and 3D reconstruction were applied to study ASC morphology and localization. Cultured cells were analyzed for changes in CD34 expression and proliferation rates. Immunostaining was performed to detect markers like NG2, CD140b, and alpha-smooth muscle actin. The spontaneous differentiation potential of ASCs was assessed in vitro. The study compared native ASCs with bone marrow-derived mesenchymal stromal cells to identify phenotypic differences.

Native ASCs were identified within the CD34(+) fraction of the adipose tissue stromal vascular fraction. These cells expressed classical mesenchymal markers similar to bone marrow-derived cells. CD34 expression decreased during culture and correlated inversely with proliferation rates. Immunohistology showed that native ASCs had distinct morphological features, including protrusions. They were scattered within the adipose tissue stroma and did not express pericytic markers like NG2 or CD140b. Pericytic markers appeared only after in vitro culture, suggesting a change in cell identity. Adipose tissue from obese individuals showed enhanced spontaneous adipocytic differentiation of ASCs. These findings suggest that native ASCs differ from cultured cells in both morphology and marker expression.

The study demonstrated that native ASCs are located in the CD34(+) fraction of the stromal vascular fraction. These cells share mesenchymal markers with bone marrow-derived cells but differ in their in vivo characteristics. Morphologically, native ASCs exhibit protrusions and are scattered within adipose tissue. They do not express pericytic markers in their native state, which emerge during culture. CD34 levels decrease during culture and correlate with proliferation rates. The spontaneous adipocytic differentiation of ASCs is enhanced in obese individuals. These findings suggest that native ASCs may play a role in adipogenesis during tissue development. The data support the view that ASCs retain stemness characteristics in their native environment.