First steps to define murine amniotic fluid stem cell microenvironment

Abstract

Stem cell niche refers to the microenvironment where stem cells reside in living organisms. Several elements define the niche and regulate stem cell characteristics, such as stromal support cells, gap junctions, soluble factors, extracellular matrix proteins, blood vessels and neural inputs. In the last years, different studies demonstrated the presence of cKit+ cells in human and murine amniotic fluid, which have been defined as amniotic fluid stem (AFS) cells. Firstly, we characterized the murine cKit+ cells present both in the amniotic fluid and in the amnion. Secondly, to analyze the AFS cell microenvironment, we injected murine YFP+ embryonic stem cells (ESC) into the amniotic fluid of E13.5 wild type embryos. Four days after transplantation we found that YFP+ sorted cells maintained the expression of pluripotency markers and that ESC adherent to the amnion were more similar to original ESC in respect to those isolated from the amniotic fluid. Moreover, cytokines evaluation and oxygen concentration analysis revealed in this microenvironment the presence of factors that are considered key regulators in stem cell niches. This is the first indication that AFS cells reside in a microenvironment that possess specific characteristics able to maintain stemness of resident and exogenous stem cells.

Development of a novel method for amniotic fluid stem cell storage

“…The expression of surface mesenchymal markers for c-kit-positive cells was tested by immunofluorescence and Western blot approaches. Since hAFSCs are defined as intermediate between pluripotent and multipotent stem cells [11], the expression of pluripotency genes, such as Oct-4, Sox-2, Nanog, and SSEA-4, has been compared.…”

In Utero Transplantation of Expanded Autologous Amniotic Fluid Stem Cells Results in Long-Term Hematopoietic Engraftment

“…B; expression of non‐CD45 hematopoietic lineage markers postisolation 0.9% ± 0.3%). Approximately 1 × 10 4 –5 × 10 4 AFSCs could be isolated from each fetus (1% of live cells found in each amniotic sac) . Freshly isolated AFSCs demonstrated near‐universal expression of CD45 (96.8% ± 2.3%), but low levels of other hematopoietic markers (Sca‐1+: 31.3% ± 74%; CD34+: 9.6% ± 3.2%) and MHC (class I/H2Kb: 9.1% ± 1.7%; Fig.…”

“…Single cell quantitative reverse‐transcription polymerase chain reaction (qRT‐PCR) analysis of AFSCs was performed as described previously (see Supporting Information Methods) . We focused our analysis on the key hematopoietic regulators GATA1, GATA2, and Lmo2, as well as the pluripotency regulators Oct4, c‐Myc, Klf4, Sox2, and Nanog.…”

Adaptation within embryonic and neonatal heart environment reveals alternative fates for adult c-kit+ cardiac interstitial cells

“…Tetraploid exclusion from the embryo and polyploidy of extra‐embryonic membranes are fundamental biological properties of development . The presence of c‐Kit + cells in murine amniotic fluid and in the amnion presents a potential permissive milieu to host transplanted cCICs and a possible mechanism for amniotic membrane engraftment. Similar to findings reported here, extra‐embryonic membrane contribution for pluripotent human ES cells follows introduction into murine blastocysts .…”