Human primary fibroblasts perform similarly to MSCs in assays used to evaluate MSC safety and potency

Abstract

BACKGROUND Cellular therapeutic agents may benefit trauma patients by modulating the immune response to injury, and by reducing inflammation and vascular leakage. Administration of allogeneic mesenchymal stromal cells (MSCs) shows some benefit in preclinical and clinical trials, but less testing has been performed with other cell types. Human primary fibroblasts (FBs) were compared to MSCs in assays designed to evaluate MSCs to determine if these assays actually evaluate properties unique to MSCs or whether related cell types perform similarly. STUDY DESIGN AND METHODS MSC‐related surface marker expression, tissue factor, and human leukocyte antigen–D related were evaluated by flow cytometry, and in vitro adipogenic and osteogenic differentiation potential were determined. Procoagulant activity was determined by thromboelastography. Two potency assays correlated with immunomodulation potential were utilized: the mixed lymphocyte reaction and indoleamine 2,3‐dioxygenase enzyme activity assays. RESULTS Human primary FBs performed similarly to MSCs in assays designed to evaluate MSC characteristics and potency. Although similar for MSC‐positive cell surface marker expression, FBs did not show robust adipose differentiation and expressed some level of markers not expected on MSCs. CONCLUSIONS Human primary FBs are very similar to human MSCs, at least in assays currently used to evaluate MSC potency. Preclinical and clinical testing are required to determine if FBs show similar activity to MSCs in vivo. If FBs show inferior activity in vivo, development of new MSC‐specific potency assays will be necessary to evaluate properties relevant to their unique clinical benefits.

Refrigerated human mesenchymal stromal cells as an alternative to cryostorage for use in clinical investigation

“…Conditioned medium was collected after 24 h and stored in aliquots at −80°C. Kynurenine was measured using a modified colorimetric assay, as described previously 19 …”

Osteogenic differentiation: a universal cell program of heterogeneous mesenchymal cells or a similar extracellular matrix mineralizing phenotype?

“…Dermal fibroblasts. Dermal fibroblasts might undergo osteogenic differentiation in a similar manner to MSCs (Christy et al, 2019). Jääger et al (2012) founded that osteogenic differentiation of fibroblasts is rather similar to MSCs.…”

Neglected No More: Emerging Cellular Therapies in Traumatic Injury

“…Identification of fibroblast-specific cellular markers has proven elusive, further limiting study of fibroblasts in vivo and limiting our understanding of their potential clinical utility. However, preliminary studies indicate that human fibroblasts display similar morphology to MSCs with similar immunophenotypic capabilities [123,124]. Similar immunomodulation capabilities to MSCs (at least in vitro) and greater relative abundance make primary fibroblasts attractive candidates for cell therapy.…”

“…However, the safety profile of heterologous human fibroblast administration has been less studied and needs further analysis. Although they are thought to be less immune-privileged than MSCs, further work is needed on this issue [119,120,124,125].…”