Effective bone regeneration through tissue engineering requires a combination of osteogenic progenitors,osteoinductive biofactors and biocompatible scaffold materials.Mesenchymal stem cells(MSCs)represent the most pro...Effective bone regeneration through tissue engineering requires a combination of osteogenic progenitors,osteoinductive biofactors and biocompatible scaffold materials.Mesenchymal stem cells(MSCs)represent the most promising seed cells for bone tissue engineering.As multipotent stem cells that can self-renew and differentiate into multiple lineages including bone and fat,MSCs can be isolated from numerous tissues and exhibit varied differentiation potential.To identify an optimal progenitor cell source for bone tissue engineering,we analyzed the proliferative activity and osteogenic potential of four commonly-used mouse MSC sources,including immortalized mouse embryonic fibroblasts(iMEF),immortalized mouse bone marrow stromal stem cells(imBMSC),immortalized mouse calvarial mesenchymal progenitors(iCAL),and immortalized mouse adipose-derived mesenchymal stem cells(iMAD).We found that iMAD exhibited highest osteogenic and adipogenic capabilities upon BMP9 stimulation in vitro,whereas iMAD and iCAL exhibited highest osteogenic capability in BMP9-induced ectopic osteogenesis and critical-sized calvarial defect repair.Transcriptomic analysis revealed that,while each MSC line regulated a distinct set of target genes upon BMP9 stimulation,all MSC lines underwent osteogenic differentiation by regulating osteogenesis-related signaling including Wnt,TGF-β,PI3K/AKT,MAPK,Hippo and JAK-STAT pathways.Collectively,our results demonstrate that adipose-derived MSCs represent optimal progenitor sources for cell-based bone tissue engineering.展开更多
To achieve a maximum compression of system matrix in positron emission tomography (PET) image reconstruction, we proposed a polygonal image pixel division strategy in accordance with rotationally symmetric PET geometr...To achieve a maximum compression of system matrix in positron emission tomography (PET) image reconstruction, we proposed a polygonal image pixel division strategy in accordance with rotationally symmetric PET geometry. Geometrical definition and indexing rule for polygonal pixels were established. Image conversion from polygonal pixel structure to conventional rectangular pixel structure was implemented using a conversion matrix. A set of test images were analytically defined in polygonal pixel structure, converted to conventional rectangular pixel based images, and correctly displayed which verified the correctness of the image definition, conversion description and conversion of polygonal pixel structure. A compressed system matrix for PET image recon was generated by tap model and tested by forward-projecting three different distributions of radioactive sources to the sinogram domain and comparing them with theoretical predictions. On a practical small animal PET scanner, a compress ratio of 12.6:1 of the system matrix size was achieved with the polygonal pixel structure, comparing with the conventional rectangular pixel based tap-mode one. OS-EM iterative image reconstruction algorithms with the polygonal and conventional Cartesian pixel grid were developed. A hot rod phantom was detected and reconstructed based on these two grids with reasonable time cost. Image resolution of reconstructed images was both 1.35 mm. We conclude that it is feasible to reconstruct and display images in a polygonal image pixel structure based on a compressed system matrix in PET image reconstruction.展开更多
基金by research grants from the Natural Science Foundation of China(82102696 to JF)the Chongqing Bayu Young Scholar Award(JF),the 2019 Chongqing Support Program for Entrepreneurship and Innovation(No.cx2019113 to JF)+4 种基金the 2019 Funding for Postdoctoral Research(Chongqing Human Resources and Social Security Bureau No.298 to JF),the National Institutes of Health(CA226303 to TCH,and DE030480 to RRR)supported by the Medical Scientist Training Program of the National Institutes of Health(T32 GM007281)supported in part by The University of Chicago Cancer Center Support Grant(P30CA014599)the National Center for Advancing Translational Sciences of the National Institutes of Health through Grant Number UL1TR002389-07.
文摘Effective bone regeneration through tissue engineering requires a combination of osteogenic progenitors,osteoinductive biofactors and biocompatible scaffold materials.Mesenchymal stem cells(MSCs)represent the most promising seed cells for bone tissue engineering.As multipotent stem cells that can self-renew and differentiate into multiple lineages including bone and fat,MSCs can be isolated from numerous tissues and exhibit varied differentiation potential.To identify an optimal progenitor cell source for bone tissue engineering,we analyzed the proliferative activity and osteogenic potential of four commonly-used mouse MSC sources,including immortalized mouse embryonic fibroblasts(iMEF),immortalized mouse bone marrow stromal stem cells(imBMSC),immortalized mouse calvarial mesenchymal progenitors(iCAL),and immortalized mouse adipose-derived mesenchymal stem cells(iMAD).We found that iMAD exhibited highest osteogenic and adipogenic capabilities upon BMP9 stimulation in vitro,whereas iMAD and iCAL exhibited highest osteogenic capability in BMP9-induced ectopic osteogenesis and critical-sized calvarial defect repair.Transcriptomic analysis revealed that,while each MSC line regulated a distinct set of target genes upon BMP9 stimulation,all MSC lines underwent osteogenic differentiation by regulating osteogenesis-related signaling including Wnt,TGF-β,PI3K/AKT,MAPK,Hippo and JAK-STAT pathways.Collectively,our results demonstrate that adipose-derived MSCs represent optimal progenitor sources for cell-based bone tissue engineering.
基金Supported by Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry and National Natural Science Foundation of China(No.10975086)
文摘To achieve a maximum compression of system matrix in positron emission tomography (PET) image reconstruction, we proposed a polygonal image pixel division strategy in accordance with rotationally symmetric PET geometry. Geometrical definition and indexing rule for polygonal pixels were established. Image conversion from polygonal pixel structure to conventional rectangular pixel structure was implemented using a conversion matrix. A set of test images were analytically defined in polygonal pixel structure, converted to conventional rectangular pixel based images, and correctly displayed which verified the correctness of the image definition, conversion description and conversion of polygonal pixel structure. A compressed system matrix for PET image recon was generated by tap model and tested by forward-projecting three different distributions of radioactive sources to the sinogram domain and comparing them with theoretical predictions. On a practical small animal PET scanner, a compress ratio of 12.6:1 of the system matrix size was achieved with the polygonal pixel structure, comparing with the conventional rectangular pixel based tap-mode one. OS-EM iterative image reconstruction algorithms with the polygonal and conventional Cartesian pixel grid were developed. A hot rod phantom was detected and reconstructed based on these two grids with reasonable time cost. Image resolution of reconstructed images was both 1.35 mm. We conclude that it is feasible to reconstruct and display images in a polygonal image pixel structure based on a compressed system matrix in PET image reconstruction.
