BACKGROUND:The proliferation and phenotypic maintenance of chondrocytes are limited under two-dimensional culture conditions.Porous microspheres serve as scaffolds,providing a three-dimensional culture environment that better mimics in vivo growth conditions.Stromal cell derived factor-1,a homeostatic cytokine with potent chemotactic effects,facilitates cell adhesion and proliferation.OBJECTIVE:To investigate the impact of stromal cell derived factor-1 grafted poly-L-lactic acid porous microspheres on the biological characteristics of chondrocytes and the formation of cartilage tissue.METHODS:(1)The effects of different concentrations of stromal cell derived factor-1 on rabbit chondrocyte proliferation,migration,and phenotypic maintenance were investigated in an in vitro setting.(2)Poly-L-lactic acid porous microspheres were prepared by double emulsion method.Stromal cell derived factor-1 was grafted onto poly-L-lactic acid porous microspheres through carbodiimide reaction.The grafting was verified by enzyme-linked immunosorbent assay and incubation with stromal cell derived factor-1-specific fluorescent antibodies.(3)Rabbit chondrocytes were inoculated on poly-L-lactic acid porous microspheres and grafted on stromal cell derived factor-1 poly-L-lactic acid porous microspheres to detect cell proliferation and adhesion.(4)The methylacrylamide-gelatin-chondrocyte complex(control group),poly-L-lactic acid porous microsphere-methylacrylamide-gelatin-chondrocyte complex(porous microsphere group),and grafted stromal cell derived factor-1 poly-L-lactic acid porous microsphere-methylacrylamide-gelatin-chondrocyte complex(porous microsphere modified group)were implanted under the skin of the back of nude mice,respectively.Samples were collected 8 weeks later and detected using histological staining and qRT-PCR for chondroblast related genes.RESULTS AND CONCLUSION:(1)Compared with 0 and 1 000 ng/mL stromal cell derived factor-1,1 and 500 ng/mL stromal cell derived factor 1 could promote the proliferation and migration of chondrocytes,and enhance the mRNA expression levels of type Ⅱ collagen,elastin,proliferating cell nuclear antigen,and Bcl-2 in chondrocytes.(2)Stromal cell derived factor-1 was successfully grafted onto poly-L-lactic acid porous microspheres with a grafting rate of 93.75%.(3)Compared with poly-L-lactic acid porous microspheres,grafted stromal cell derived factor-1 poly-L-lactic acid porous microspheres promoted the proliferation and adhesion of chondrocytes.(4)After 8 weeks of subcutaneous implantation in nude mice,compared with the control group and the porous microsphere group,the porous microsphere modified group had clearer cartilage lacunae structure,more chondro-specific matrix and type Ⅱ collagen deposition,and increased expression of elastin,type Ⅱ collagen,proliferating cell nuclear antigen,and Bcl-2 mRNA.These findings indicate that stromal cell derived factor-1 grafted poly-L-lactic acid porous microspheres are beneficial to chondrocyte adhesion,proliferation,phenotypic maintenance,and the formation of cartilage tissue in vivo.

Objective:To elucidate the regulatory role of matrix metallopeptidase 14 (MMP14) in the migration of chondrogenic precursor cells, thereby providing data support for investigating the pathogenesis of microtia.Methods:An in vitro differentiation model was established using human induced pluripotent stem cells (iPSCs) sequentially induced into neural crest cells (iNCCs) and subsequently into chondrogenic precursor cells (iCPCs), combined with lentivirus-mediated knockdown of MMP14, to investigate the effects of MMP14 on the biological characteristics of iCPCs, including proliferation, differentiation, and migration. Collective cell migration was assessed using scratch wound healing and Transwell migration assays; directional migration was characterized via high-content live-cell imaging; single-cell adhesion force was measured using a micromanipulation system. Collagen degradation was evaluated through hydroxyproline digestion assays. Cell proliferation was analyzed using the CCK-8 assay, and the expression of osteogenic/chondrogenic-related genes (SOX5/6/9, COL1A1, COL2A1, RUNX2, TWIST1) were quantified by real-time quantitative PCR. Immunofluorescence staining was used to assess the expression of F-actin and CD44 proteins. Additionally, transcriptomic sequencing was performed on iCPCs before and after MMP14 knockdown. Results:iPSC→iNCC→iCPC differentiation model was established in vitro. The resulting iCPCs expressed osteo/chondrogenic marker genes, including SOX5, SOX6, SOX9, COL1A1, COL2A1, RUNX2, and TWIST1, and exhibited positive expression of mesenchymal stem cell markers CD90, CD105, and CD73. Upon further induction, functional cartilage spheroids were formed. Compared with normal auricular chondrocytes, auricular chondrocytes from microtia patients showed reduced expression of MMP14 at both mRNA and protein levels. Lentivirus-mediated shRNA knockdown of MMP14 in iCPCs resulted in a marked decrease in its mRNA and protein expression. MMP14 knockdown significantly impaired collective migration of iCPCs, as evidenced by reduced wound closure rates in scratch assays and decreased numbers of migrated cells in Transwell assays. High-content live-cell imaging revealed that MMP14-deficient iCPCs displayed more erratic migration trajectories and a lower straight-line migration ratio. Single-cell adhesion assays showed extracellular matrix (ECM)-dependent alterations: cell adhesion was enhanced on matrigel-coated surfaces but weakened under uncoated conditions. MMP14 knockdown also led to reduced proliferation, decreased collagen degradation, diminished F-actin expression, fewer peripheral adhesion sites, and downregulation of CD44 protein expression, without significantly affecting the expression of chondrogenic genes such as SOX6, SOX9, COL1A1, COL2A1, RUNX2, and TWIST1. Transcriptomic analysis further revealed that MMP14 knockdown significantly downregulated genes involved in extracellular matrix organization, cell adhesion, migration, and tissue development, with enrichment in pathways including ECM-receptor interaction, focal adhesion, and MAPK signaling. Conclusion:MMP14 plays a critical role in the directional migration of chondrogenic precursor cells by regulating ECM remodeling, adhesion signaling, and cytoskeletal proteins.

Objective:To elucidate the regulatory role of matrix metallopeptidase 14 (MMP14) in the migration of chondrogenic precursor cells, thereby providing data support for investigating the pathogenesis of microtia.Methods:An in vitro differentiation model was established using human induced pluripotent stem cells (iPSCs) sequentially induced into neural crest cells (iNCCs) and subsequently into chondrogenic precursor cells (iCPCs), combined with lentivirus-mediated knockdown of MMP14, to investigate the effects of MMP14 on the biological characteristics of iCPCs, including proliferation, differentiation, and migration. Collective cell migration was assessed using scratch wound healing and Transwell migration assays; directional migration was characterized via high-content live-cell imaging; single-cell adhesion force was measured using a micromanipulation system. Collagen degradation was evaluated through hydroxyproline digestion assays. Cell proliferation was analyzed using the CCK-8 assay, and the expression of osteogenic/chondrogenic-related genes (SOX5/6/9, COL1A1, COL2A1, RUNX2, TWIST1) were quantified by real-time quantitative PCR. Immunofluorescence staining was used to assess the expression of F-actin and CD44 proteins. Additionally, transcriptomic sequencing was performed on iCPCs before and after MMP14 knockdown. Results:iPSC→iNCC→iCPC differentiation model was established in vitro. The resulting iCPCs expressed osteo/chondrogenic marker genes, including SOX5, SOX6, SOX9, COL1A1, COL2A1, RUNX2, and TWIST1, and exhibited positive expression of mesenchymal stem cell markers CD90, CD105, and CD73. Upon further induction, functional cartilage spheroids were formed. Compared with normal auricular chondrocytes, auricular chondrocytes from microtia patients showed reduced expression of MMP14 at both mRNA and protein levels. Lentivirus-mediated shRNA knockdown of MMP14 in iCPCs resulted in a marked decrease in its mRNA and protein expression. MMP14 knockdown significantly impaired collective migration of iCPCs, as evidenced by reduced wound closure rates in scratch assays and decreased numbers of migrated cells in Transwell assays. High-content live-cell imaging revealed that MMP14-deficient iCPCs displayed more erratic migration trajectories and a lower straight-line migration ratio. Single-cell adhesion assays showed extracellular matrix (ECM)-dependent alterations: cell adhesion was enhanced on matrigel-coated surfaces but weakened under uncoated conditions. MMP14 knockdown also led to reduced proliferation, decreased collagen degradation, diminished F-actin expression, fewer peripheral adhesion sites, and downregulation of CD44 protein expression, without significantly affecting the expression of chondrogenic genes such as SOX6, SOX9, COL1A1, COL2A1, RUNX2, and TWIST1. Transcriptomic analysis further revealed that MMP14 knockdown significantly downregulated genes involved in extracellular matrix organization, cell adhesion, migration, and tissue development, with enrichment in pathways including ECM-receptor interaction, focal adhesion, and MAPK signaling. Conclusion:MMP14 plays a critical role in the directional migration of chondrogenic precursor cells by regulating ECM remodeling, adhesion signaling, and cytoskeletal proteins.

BACKGROUND:The proliferation and phenotypic maintenance of chondrocytes are limited under two-dimensional culture conditions.Porous microspheres serve as scaffolds,providing a three-dimensional culture environment that better mimics in vivo growth conditions.Stromal cell derived factor-1,a homeostatic cytokine with potent chemotactic effects,facilitates cell adhesion and proliferation.OBJECTIVE:To investigate the impact of stromal cell derived factor-1 grafted poly-L-lactic acid porous microspheres on the biological characteristics of chondrocytes and the formation of cartilage tissue.METHODS:(1)The effects of different concentrations of stromal cell derived factor-1 on rabbit chondrocyte proliferation,migration,and phenotypic maintenance were investigated in an in vitro setting.(2)Poly-L-lactic acid porous microspheres were prepared by double emulsion method.Stromal cell derived factor-1 was grafted onto poly-L-lactic acid porous microspheres through carbodiimide reaction.The grafting was verified by enzyme-linked immunosorbent assay and incubation with stromal cell derived factor-1-specific fluorescent antibodies.(3)Rabbit chondrocytes were inoculated on poly-L-lactic acid porous microspheres and grafted on stromal cell derived factor-1 poly-L-lactic acid porous microspheres to detect cell proliferation and adhesion.(4)The methylacrylamide-gelatin-chondrocyte complex(control group),poly-L-lactic acid porous microsphere-methylacrylamide-gelatin-chondrocyte complex(porous microsphere group),and grafted stromal cell derived factor-1 poly-L-lactic acid porous microsphere-methylacrylamide-gelatin-chondrocyte complex(porous microsphere modified group)were implanted under the skin of the back of nude mice,respectively.Samples were collected 8 weeks later and detected using histological staining and qRT-PCR for chondroblast related genes.RESULTS AND CONCLUSION:(1)Compared with 0 and 1 000 ng/mL stromal cell derived factor-1,1 and 500 ng/mL stromal cell derived factor 1 could promote the proliferation and migration of chondrocytes,and enhance the mRNA expression levels of type Ⅱ collagen,elastin,proliferating cell nuclear antigen,and Bcl-2 in chondrocytes.(2)Stromal cell derived factor-1 was successfully grafted onto poly-L-lactic acid porous microspheres with a grafting rate of 93.75%.(3)Compared with poly-L-lactic acid porous microspheres,grafted stromal cell derived factor-1 poly-L-lactic acid porous microspheres promoted the proliferation and adhesion of chondrocytes.(4)After 8 weeks of subcutaneous implantation in nude mice,compared with the control group and the porous microsphere group,the porous microsphere modified group had clearer cartilage lacunae structure,more chondro-specific matrix and type Ⅱ collagen deposition,and increased expression of elastin,type Ⅱ collagen,proliferating cell nuclear antigen,and Bcl-2 mRNA.These findings indicate that stromal cell derived factor-1 grafted poly-L-lactic acid porous microspheres are beneficial to chondrocyte adhesion,proliferation,phenotypic maintenance,and the formation of cartilage tissue in vivo.