ObjectiveTo assess the role and effect of Wharton's jelly of human umbilical cord oriented scaffold on chondrocytes co-cultured in vitro. MethodsChondrocytes from shoulder cartilage of adult New Zealand rabbits were isolated,cultured,amplified,and labelled using fluorescent dye PKH26.Cells were extracted from human umbilical cord tissue using wet-grinding chemical technology to prepare the Wharton's jelly of human umbilical cord oriented scaffold by freeze-drying and cross-linking technology.Second generation of chondrocytes were cultured with Wharton's jelly of human umbilical cord oriented scaffold.Inverted microscope and scanning electron microscope (SEM) were used to observe the cell distribution and adhesion on the scaffold; extracellular matrix secretion of the chondrocytes were observed by toluidine blue and safranin O staining.Cells distribution and proliferation on the scaffold were assessed by fluorescein diacetate-propidium iodide (FDA-PI) and Hoechst33258 staining.The viability of the in vitro cultured and PKH26 fluorescence labelled chondrocytes on the scaffold were assessed via fluorescence microscope. ResultsInverted microscope showed that the cells cultured on the scaffold for 3 days were round or oval shaped and evenly distributed into space of the scaffold.SEM observation showed that large number of cultured cells adhered to the pores between the scaffolds and were round or oval shape,which aggregated,proliferated,and arranged vertically on longitudinally oriented scaffold at 7 days after culture.Histological observation showed that cells distributed and proliferated on the scaffold,and secreted large amount of extracellular matrix at 7 days.Scaffold could guide cell migration and proliferation,and could effectively preserve and promote the secretion of extracellular matrix.Cell viability assessments at 3 days after culture showed most of the adhered cells were living and the viability was more than 90%.PKH26 labelled chondrocytes were seen,which distributed uniformly along the pore of oriented scaffold,and exuberantly proliferated. ConclusionWharton's jelly of human umbilical cord oriented scaffold favors adhesion,proliferation,and survival of chondrocytes.It possesses a favorable affinity and cell compatibility.Thus,it is an ideal scaffold for cartilage tissue engineering.
ObjectiveTo introduce a technique of frozen sections for undecalcified bone and discuss its feasibility by observing the fluorescence distribution of the bone and cartilage. MethodsThe male Sprague Dawley transgenic rats at the age of 8 weeks, which express green fluorescent protein were selected to isolate the whole knee sectioned by the undecalcified bone frozen section technique. Under the fluorescence and light microscopy, the fluorescence and structure were observed within the organization of slice. Immunohistochemical staining (collagen type Ⅰ and Ⅱ), HE staining, toluidine blue staining, and Alizarin red staining were performed to observe the distribution of fluorescent substance and cartilage and bone structure. ResultsThe thickness of sections prepared by this technology was 6 μm. General observation showed that the structure of sectioned joint was complete. Under the light microscope, the morphology of cartilage cells, the arrangement of subchondral bone, and trabecular bone traveling could be clearly distinguished. Under fluorescence microscope, green fluorescence was shown in the joint soft tissue, cartilage tissue, and bone tissue; collagen type Ⅰ expressed in the bone tissue, collagen type Ⅱ in cartilage tissue. HE staining and toluidine blue staining could clearly distinguish the morphology of the cartilage layer. Alizarin red staining showed the structural integrity of subchondral bone plate and the organization within the meniscus, and proximal tibia cortical bone continuity. ConclusionThe fluorescence distribution can be directly observe in the bone and cartilage by sectioning of frozen undecalcified bone. This new technology can shorten the cycle of preparing sections.