Abstract
Purpose::
Myofibroblasts play an important role in morphogenesis and oncogenesis, inflammation, wound healing and fibrosis in most tissues. Amniotic membrane stroma can maintain keratocytes in cultures and prevent them from turning into myofibroblasts. It remains unknown whether it can also reverse differentiated myofibroblasts.
Methods::
Human amniotic membrane stromal cells (AMSC) harvested by collagenase digestion of AM stroma were cultured in DMEM with 10% FBS (DMEM/FBS). Amniotic membrane stromal extract (ASE) was prepared from cryopreserved amniotic membrane. In vivo and vitro phenotype of AMSCs were determined by immunostaining to α-SMA, desmin, and vimentin and by immunobloting of ED-A fibronectin and α-SMA. Cell proliferation was determined by immunostaining of Ki67.
Results::
In vivo AMSCs adopted a dendritic shape, and expressed vimentin but not α-SMA nor desmin. Once cultured in DMEM/FBS on plastic, they quickly and completely differentiated into α-SMA-expressing myofibroblasts within 2 passages. However, these myofibroblasts lost their α-SMA expression and reduced ED-A fibronectin expression when re-seeded back to AM stromal surface, while continued to maintain their myofibroblastic phenotype on type I collagen. Primary AMSCs cultures in DMEM/FBS showed cell aggregation and weak expression of α-SMA if added ASE. Differentiated myofibroblasts from P2 AMSCs cultures in DMEM with or without FBS changed their cell shape from squamous to spindle or dendritic, and markedly reduced expression of ED-A fibronectin and α-SMA when added with ASE.
Conclusions::
Amniotic membrane stroma contains soluble factors that may not only help maintain the normal phenotype of AMSCs, but also reverse differentiated myofibroblasts back to the fibroblast phenotype. Further investigation into their identity and mechanism may unravel a new scar-reversing strategy.
Keywords: differentiation • extracellular matrix