Isolation and Characterization of an Adult Stem Cell Population from Human Epidural Fat

Abstract

Study Design. Isolation and characterization of human epidural fat (HEF) stem/progenitor cells. Objective. To identify a progenitor population within HEF and to determine if they meet the minimal criteria of a mesenchymal stem cell (MSC). Summary of Background Data. The biological function, if any, has yet to be determined for HEF. The presence of MSCs within HEF may indicate a regenerative potential within the HEF. Methods. HEF was isolated from 10 patients during elective spinal surgery. HEF cells were differentiated along osteo-, adipo-, and chondrogenic lineages, with differentiation analyzed via qPCR and histology. The cell surface receptor profile of HEF cells was examined by flow cytometry. HEF cells were also assayed through the collagen contraction assay. Prx1CreERT2GFP:R26RTdTomato MSC lineage-tracking mice were employed to identify EF MSCs in vivo. Results. HEF cell lines were obtained from all 10 patients in the study. Cells from 2/10 patients demonstrated full MSC potential, while cells from 6/10 patients demonstrated progenitor potential; 2/10 patients presented with cells that retained only adipogenic potential. HEF cells demonstrated MSC surface marker expression. All patient cell lines contracted collagen gels. A Prx1-positive population in mouse epidural fat that appeared to contribute to the dura of the spinal cord was observed in vivo. Conclusions. MSC and progenitor populations are present within HEF. MSCs were not identified in all patients examined in the current study. Furthermore, all patient lines demonstrated collagen contraction capacity, suggesting either a contaminating activated fibroblast population or HEF MSCs/progenitors also demonstrating a fibroblast-like phenotype. In vivo analysis suggests that these cell populations may contribute to the dura. Overall, these results suggest that cells within epidural fat may play a biological role within the local environment above providing a mechanical buffer.

Epidural fat mesenchymal stem cells: Important microenvironmental regulators in health, disease, and regeneration

“…As a specific example, in our teams’ previous study on EF‐MSCs, we were able to demonstrate that the EF‐MSCs also contribute to the dura mater. [ 57 ] Based on this result, it would be important to determine if ADSCs derived from non‐epidural fat sources can also migrate and populate the dura mater. While we demonstrated EF‐MSCs are present in the dura mater, [ 57 ] the role of these cells in the dura remain unknown.…”

“…[ 57 ] Based on this result, it would be important to determine if ADSCs derived from non‐epidural fat sources can also migrate and populate the dura mater. While we demonstrated EF‐MSCs are present in the dura mater, [ 57 ] the role of these cells in the dura remain unknown. It will be essential to determine if EF‐MSCs contribute to the maintenance and/or repair of the dura mater and if other ADSCs populations (from other fat sources) could also replicate this EF‐MSC function.…”

“…[ 76 ] Given that EF‐MSCs were only recently discovered, and their role in vivo remains elusive, it is not surprising that little investigation has been undertaken on endogenous dural repair mechanisms. To our knowledge, there are currently no methods to induce endogenous dural repair, and therefore, if EF‐MSCs play a role in dural maintenance, [ 57 ] then it is possible that cells within the epidural fat could be mobilized in dural repair strategies. While no direct evidence exists to support this hypothesis, given that the debridement/destruction of epidural fat results in a pro‐inflammatory and pro‐fibrotic response, EF‐MSCs can be tracked to the dura mater in vivo , and damage to the dura mater can result in a myriad of complications including death; we believe that some type of endogenous repair mechanism exists in regard to the dura otherwise clinical interventions required for dural repair would be much more common.…”

“…Only recently have human epidural fat MSCs (EF‐MSCs) been isolated and found to retain self‐renewal and trilineage differentiation capacity in vitro. [ 56,57 ] Through the use of lineage‐tracing mouse models, EF‐MSCs were identified in vivo , with their progeny appearing to contribute to the dura mater. [ 57 ] The existence of EF‐MSCs suggests that epidural fat is not solely a space filling tissue and therefore we hypothesize that: the loss of epidural fat and/or EF‐MSCs will result in increased inflammation, fibrosis, and degeneration of adjacent tissues (such as dura) within the vertebral environment.…”

Differentiation Potential And Tumorigenic Risk of Rat Bone Marrow Stem Cells Are Affected By Long-Term In Vitro Expansion

“…Mesenchymal stem cells (MSCs) have the capacity for extensive expansion in vitro and are able to undergo adipogenic, osteogenic, chondrogenic, myogenic, and neural differentiation [1,2,3]. MSCs can be obtained from several sources, such as placental tissue [4], amniotic fluid [5], cord blood [6,7], adipose tissue [8,9], and dental pulp [10]. However, bone marrow aspiration remains the source of choice for MSCs in most laboratories [11,12].…”