Characteration Of Antler Stem Cells And Exploration Of Key Regulatory Factors In Antler Regeneration

Mammalian organ regeneration is the “Holy Grail” of modern regenerative biology and medicine.The most dramatic and difficult organ regeneration is known as epimorphic regeneration,i.e.regeneration of a replica of the lost part from the distal end of a leg/arm stump.To date our knowledge of epimorphic regeneration has come from studies of low amphibians.Taken newt as an example,they have the ability to reprogram phenotypically committed cells to form a blastema,which is composed of dedifferentiated cells.Deer antlers are the only mammalian appendages capable of full renewal,and therefore offer a unique model for study of mammalian epimorphic regeneration.Histological examinations and animal experiments domestrated that antler regeneration is a stem cell-based epimorphic process.This is markedly different from that of amphibian limb regeneration,i.e.blastema-based process.Antler stem cells(ASCs)reside in the antlerorgenic periosteum,pedicle periosteum and mesenchyme in antler tips.Identifacation and exploration of key regulatory factors in ASCs is a main way to reveal the mechanism underlying antler regeneration.In this study,we focused on ASCs,and systematically compared difference between the ASCs and mesenchymal stem cells at cell,protein and transcriprition levels.We focused on patterns of differentially expressed genes and active pathways in antler stem cells through proteome and transcriptome approaches.We wish to find key regulatory factors that regulate ASCs.The results showed that ASCs were not significantly different from the facial periosteal cells(control)in cell proliferion,apoptosis,and cell cycle distribution.Monoclony formation capability of ASCs was significantly higher than that of the somatic periosteal cells.We failed to find embryonic stem cell markers such as Oc4,Nanog that were expressed in ASCs.Classical markers for mesenchymal stem cells such as CD73,CD90,CD105 and Stro-1 were found in the ASCs.In addition,ASCs highly expressed Nestin,a marker for neural stem cells.Based on the results of transcriptome sequencing,402 unigenes were functionally annotated and found to be related to stem cells using transcriptome profiling.These GO terms associated with “stem cell” including “development”,“maintenance”,“differentiation”,“division”,“proliferation” and “migration”.Of these selected unigenes,220 were assigned to “stem cell maintenance” that comprised the majority of the GO terms of stem cells.Among these stem cell related genes,25 matches those that are expressed in the embryonic stem cells(50 genes in total);11 in the mesenchymal stem cells(13 genes in total),and 19 in the osteoprogenitor cells(24 genes in total).Therefore,ASCs could be placed in an intermediate category between embryonic and mesenchymal stem cells.The results provided differentially expressed genes in the ASCs(1413?and 1253?))over the facial periosteal cells.GO enrichment and clustering analyses are related to process of stem cell maintenance,differentiation,proliferation,histone methylation and DNA methylation,including cell proliferation and apoptosis,cell cycle process and NOD-like receptor signaling pathway.Base on proteome study,we identified 96 differentially expressed proteins in total.Those proteins related to cell proliferation and apoptosis,mitosis,glycolysis,cell cycle process and NOD-like receptor signaling pathway.tumor related factors HSP90,HSP47,Galectin-1 and S100A4 were found highly expressed in the ASCs.In conclution: 1)ASCs were not significantly different from somatic periosteal cells in cell proliferion,apoptosis,cell cycle distribution;2)Classical markers for mesenchymal stem cells such as CD73,CD90,CD105 and Stro-1,were fund to be expressed in the ASCs;3)Differentially expressed genes were related to process of stem cell maintenance,differentiation,proliferation,histone methylation and DNA methylation.Differerantially expressed proteins were found to be related to cell proliferation and apoptosis,mitosis,glycolysis,cell cycle process and NOD-like receptor signaling pathway.4)Correlation between transcriptome and proteome was evaluated: to single gene or protein,the consistency was weak,however,when extended to biological process or signal pathway,the consistency is very high.