ObjectiveTo prepare dopamine modified and cartilage derived morphogenetic protein 1 (CDMP1) laden polycaprolactone-hydroxyapatite (PCL-HA) composite scaffolds by three-dimensional (3D) printing and evaluate the effect of 3D scaffolds on in vitro chondrogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs).MethodsA dimensional porous PCL-HA scaffold was fabricated by 3D printing. Dopamine was used to modify the surface of PCL-HA and then CDMP-1 was loaded into scaffolds. The surface microstructure was observed by scanning electron microscope (SEM) and porosity and water static contact angle were also detected. The cytological experiment in vitro were randomly divided into 3 groups: group A (PCL-HA scaffolds), group B (dopamine modified PCL-HA scaffolds), and group C (dopamine modified and CDMP-1 laden PCL-HA scaffolds). The hBMSCs were seeded into three scaffolds, in chondrogenic culture conditions, the cell adhesive rate, the cell proliferation (MTT assay), and cell activity (Live-Dead staining) were analyzed; and the gene expressions of collagen type Ⅱ and Aggrecan were detected by real-time fluorescent quantitative PCR.ResultsThe scaffolds in 3 groups were all showed a cross-linked and pore interconnected with pore size of 400–500 μm, porosity of 56%, and fiber orientation of 0°/90°. For dopamine modification, the scaffolds in groups B and C were dark brown while in group A was white. Similarly, water static contact angle was from 76° of group A to 0° of groups B and C. After cultured for 24 hours, the cell adhesion rate of groups A, B, and C was 34.3%±3.5%, 48.3%±1.5%, and 57.4%±2.5% respectively, showing significant differences between groups (P<0.05). Live/Dead staining showed good cell activity of cells in 3 groups. MTT test showed that hBMSCs proliferated well in 3 groups and the absorbance (A) value was increased with time. The A value in group C was significantly higher than that in groups B and A, and in group B than in group A after cultured for 4, 7, 14, and 21 days, all showing significant differences (P<0.05). The mRNA relative expression of collagen type Ⅱ and Aggrecan increased gradually with time in 3 groups. The mRNA relative expression of collagen type Ⅱafter cultured for 7, 14, and 21 days, and the mRNA relative expression of Aggrecan after cultured for 14 and 21 days in group C were significantly higher than those in groups A and B, and in group B than in group A, all showing significant differences (P<0.05).ConclusionCo-culture of dopamine modified and CDMP1 laden PCL-HA scaffolds and hBMSCs in vitro can promote hBMSCs’ adhesion, proliferation, and chondrogenic differentiation.
ObjectiveElectrospinning technique was used to manufacture polycaprolactone (PCL)/collagen typeⅠ nanofibers orientated patches and to study their physical and chemical characterization, discussing their feasibility as synthetic patches for rotator cuff repairing.MethodsPCL patches were prepared by electrospinning with 10% PCL electrospinning solution (control group) and PCL/collagen typeⅠorientated nanofibers patches were prepared by electrospinning with PCL electrospinning solution with 25% collagen type Ⅰ(experimental group). The morphology and microstructure of the two patches were observed by gross and scanning electron microscopy, and the diameter and porosity of the fibers were measured; the mechanical properties of the patches were tested by uniaxial tensile test; the composition of the patches was analyzed by Fourier transform infrared spectroscopy; and the contact angle of the patch surface was measured. Two kinds of patch extracts were co-cultured with the third generation of rabbit tendon stem cells. Cell counting kit 8 (CCK-8) was used to detect the toxicity and cell proliferation of the materials. Normal cultured cells were used as blank control group. Rabbit tendon stem cells were co-cultured with the two patches and stained with dead/living cells after 3 days of in vitro culture, and laser confocal scanning microscopy was used to observe the cell adhesion and activity on the patch.ResultsGross and scanning electron microscopy showed that the two patch fibers were arranged in orientation. The diameter of patch fibers in the experimental group was significantly smaller than that in the control group (t=26.907, P=0.000), while the porosity in the experimental group was significantly larger than that in the control group (t=2.506, P=0.032). The tensile strength and Young’s modulus of the patch in the experimental group were significantly higher than those in the control group (t=3.705, P=0.029; t=4.064, P=0.034). Infrared spectrum analysis showed that PCL and collagen type Ⅰ were successfully mixed in the experimental group. The surface contact angle of the patch in the experimental group was (73.88±4.97)°, which was hydrophilic, while that in the control group was (128.46±5.10) °, which was hydrophobic. There was a significant difference in the surface contact angle between the two groups (t=21.705, P=0.002). CCK-8 test showed that with the prolongation of culture time, the cell absorbance (A) value increased gradually in each group, and there was no significant difference between the experimental group and the control group at each time point (P>0.05). Laser confocal scanning microscopy showed that rabbit tendon stem cells could adhere and grow on the surface of both patches after 3 days of culture. The number of cells adhered to the surface of the patches in the experimental group was more than that in the control group, and the activity was better.ConclusionPCL/ collagen type Ⅰ nanofibers orientated patch prepared by electrospinning technology has excellent physical and chemical properties, cell adhesion, and no cytotoxicity. It can be used as an ideal scaffold material in tendon tissue engineering for rotator cuff repair in the future.
Objective To investigate the effect of icarin/attapulgite/collagen type Ⅰ/polycaprolactone (ICA/ATP/Col Ⅰ/PCL) composite scaffold in repair of rabbit tibia defect. Methods The ICA/20%ATP/Col Ⅰ/PCL (scaffold 1), ICA/30%ATP/Col Ⅰ/PCL (scaffold 2), 20%ATP/Col Ⅰ/PCL (scaffold 3), and 30%ATP/Col Ⅰ/PCL (scaffold 4) composite scaffolds were constructed by solution casting-particle filtration method. The structure characteristics of the scaffold 2 before and after cross-linking were observed by scanning electron microscopy, and the surface contact angles of the scaffold 2 and the scaffold 4 were used to evaluate the water absorption performance of the material. The in vitro degradation test was used to evaluate the sustained-release effect of the scaffold 2. Thirty male Japanese white rabbits, weighing (2.0±0.1) kg, were randomly divided into groups A, B, C, D, and E, 6 in each group. After making a 1 cm- diameter bilateral tibial defects model, group A was the defect control group without any material implanted. Groups B, C, D, and E were implanted with scaffolds 3, 4, 1, and 2 at the defect sites, respectively. At 4, 8, and 12 weeks after operation, the repairing effects of 4 scaffolds were observed by gross observation, histological observation of HE and Masson staining, and immunohistochemical staining of osteogenic specific transcription factor (runt-related transcription factor 2, RUNX2), osteogenic related transcription factor [Osterix (OSX), Col Ⅰ, osteopontin (OPN)]. Results Scanning electron microscopy observation showed that the scaffolds were all porous. The structure of the material was loose before and after cross-linking. The surface contact angle showed that the scaffold was hydrophobic, and the scaffold 2 was more hydrophobic than scaffold 4. The sustained-release effect in vitro showed that the drug could be released in a micro and long-term manner. In the animal implantation experiment, the gross observation showed that the defects were significantly smaller in groups D and E than in groups A, B, and C at 4 and 12 weeks after operation. HE and Masson staining showed that the defect of group A was full of connective tissue at 4 weeks after operation, a large number of fibers were seen in groups B and C, and the new bone formation was observed in groups D and E. The increase of new bone was observed in each group at 8 weeks after operation. The defect of group A was still dominated by connective tissue at 12 weeks after operation, and a small amount of new bone tissue was observed in groups B and C, and a large number of new bone tissue was observed in groups D and E, especially in group E, and most of the materials degraded. Immunohistochemical staining showed that the expressions of RUNX2 and OSX in the new tissues of groups D and E were significantly higher than those of the other groups at 4 weeks after operation. The expression of RUNX2 decreased at 8 and 12 weeks after operation. After 8 weeks and 12 weeks, the expressions of Col Ⅰand OPN increased than in 4 weeks. And the expressions of Col Ⅰ and OPN in the new tissues of groups D and E were significantly more than those of the other groups. Conclusion ICA/ATP/Col I/PCL composite scaffolds have good porosity and biocompatibility, can promote bone formation, and have good bone regeneration and repair effect.
ObjectiveTo construction the telmisartan/collagen/polycaprolactone (PCL) nerve conduit and assess its effect on repairing sciatic nerve defect in rats. Methods The 60% collagen/hexafluoroisopropanol (HFIP) solution and 40% PCL/HFIP solution were prepared and mixed (collagen/PCL solution). Then the 0, 5, 10, and 20 mg of telmisartan were mixed with the 10 mL collagen/PCL solution, respectively. Telmisartan/collagen/PCL nerve conduits were fabricated via high voltage electrospinning technology. The structure of nerve conduit before and after crosslinking was observed by using scanning electron microscope (SEM). The drug release efficiency was detected by in vitro sustained release method. RAW264.7 cells were cultured with lipopolysaccharide to induce inflammation, and then co-cultured with nerve conduits loaded with different concentrations of telmisartan for 24 hours. The mRNA expressions of inducible nitric oxide synthase (iNOS) and Arginase 1 (Arg-1) were detected by using real-time fluorescence quantitative PCR. Forty adult Wistar rats were randomly divided into 4 groups (n=10). After preparing 15-mm-long sciatic nerve defect, the defect was repaired by cross-linked nerve conduits loaded with 0, 5, 10, and 20 mg telmisartan in groups A, B, C, and D, respectively. After operation, the general condition of rats was observed after operation; the sciatic function index (SFI) was tested; the bridging between the nerve conduit and sciatic nerve, and the integrity of nerve conduit were observed; the tissue growth in nerve conduit and material degradation were observed by HE staining; the expressions of CD86 (M1 macrophage marker), CD206 (M2 macrophage marker), myelin basic protein (MBP), and myelin protein 0 (P0) in new tissues were also observed by immunohistochemical staining; the expressions of neurofilament 200 (NF-200) and S-100β in new tissues were assessed by immunofluorescence staining. Results The general observation showed that the inner diameter of the nerve conduit was 1.8 mm and the outer diameter was 2.0 mm. After cross-linking by genipin, the nanofiber became thicker and denser. The drug release test showed that the telmisartan loaded nerve conduit could be released gradually. With the increase of telmisartan content in nerve conduit, the iNOS mRNA expression decreased and the Arg-1 mRNA expression increased; and the differences between 20 mg group and other groups were significant (P<0.05). In vivo experiment showed that all animals in each group survived until the completion of the experiment. The SFI was significantly higher in groups C and D than in groups A and B at different time points (P<0.05) and in group D than in group C at 6 months after operation (P<0.05). HE staining showed that there were significantly more new tissues in the middle of the nerve conduit in group D after operation than in other groups. Immunohistochemical staining showed that CD86 and CD206 stainings were positive in each group at 1 month after operation, among which group D had the lowest positive rate of CD86 and the highest positive rate of CD206, and there were significant differences in the positive rate of CD206 between group D and groups A, B, and C (P<0.05); the MBP and P0 stainings were positive in groups C and D at 6 months, and the positive rate in group D was significantly higher than that in group C (P<0.05). Immunofluorescence staining showed that the NF-200 and S-100β expressions in group D were significantly higher than those in other groups. ConclusionTelmisartan/collagen/PLC nerve conduit can promote the sciatic nerve defect repair in rats through promoting the polarization of M1 macrophages to M2 macrophages, and the nerve conduit loaded with20 mg telmisartan has the most significant effect.
ObjectiveTo provide experimental data and theoretical support for further studying the maturity of cardiac patches in other in vitro experiments and the safety in other in vivo animal experiments, through standard chemically defined and small molecule-based induction protocol (CDM3) for promoting the differentiation of human induced pluripotent stem cells (hiPSCs) into myocardium, and preliminarily preparing cardiac patches. MethodsAfter resuscitation, culture and identification of hiPSCs, they were inoculated on the matrigel-coated polycaprolactone (PCL). After 24 hours, the cell growth was observed by DAPI fluorescence under a fluorescence microscope, and the stemness of hiPSCs was identified by OCT4 fluorescence. After fixation, electron microscope scanning was performed to observe the cell morphology on the surface of the patch. On the 1st, 3rd, 5th, and 7th days of culture, the cell viability was determined by CCK-8 method, and the growth curve was drawn to observe the cell growth and proliferation. After co-cultured with matrigel-coated PCL for 24 hours, hiPSCs were divided into a control group and a CDM3 group, and continued to culture for 6 days. On the 8th day, the cell growth was observed by DAPI fluorescence under a fluorescence microscope, and hiPSCs stemness was identified by OCT4 fluorescence, and cTnT and α-actin for cardiomyocyte marker identification. ResultsImmunofluorescence of hiPSCs co-cultured with matrigel-coated PCL for 24 hours showed that OCT4 emitted green fluorescence, and hiPSCs remained stemness on matrigel-coated PCL scaffolds. DAPI emitted blue fluorescence: cells grew clonally with uniform cell morphology. Scanning electron microscope showed that hiPSCs adhered and grew on matrigel-coated PCL, the cell outline was clearly visible, and the morphology was normal. The cell viability assay by CCK-8 method showed that hiPSCs proliferated and grew on PCL scaffolds coated with matrigel. After 6 days of culture in the control group and the CDM3 group, immunofluorescence showed that the hiPSCs in the control group highly expressed the stem cell stemness marker OCT4, but did not express the cardiac markers cTnT and α-actin. The CDM3 group obviously expressed the cardiac markers cTnT and α-actin, but did not express the stem cell stemness marker OCT4. ConclusionhiPSCs can proliferate and grow on matrigel-coated PCL. Under the influence of CDM3, hiPSCs can be differentiated into cardiomyocyte-like cells, and the preliminary preparation of cardiac patch can provide a better treatment method for further clinical treatment of cardiac infarction.
Objective To develop a biodegradable implantable bone material with compatible mechanics with the bone tissue, providing a new biomaterial for clinical bone repair and regeneration. Methods Silk reinforced polycaprolactone composites (SPC) containing 20%, 40%, and 60% silk were prepared by layer-by-layer assembly and hot-pressing technology. Macroscopic morphology was observed and microstructure were observed by scanning electron microscopy, compressive mechanical properties were detected by compression test, surface wettability was detected by surface contact angle test, degradation of materials was observed after soaking in PBS for 180 days, and proliferation of MC3T3-E1 cells was detected by cell counting kit 8 assay. Six Sprague Dawley rats were subcutaneously implanted with polycaprolactone (PCL) and 20%-SPC, respectively. Masson staining was used to analyze the in vivo degradation behavior and vascularization effect within 180 days. Results The pore defects of the three SPC sections were relatively few. In the range of 20% to 60%, as the silk content increased and the PCL content decreased, the interlayer spacing of silk fabric decreased, and the fibers almost covered the entire cross-section. The compressive modulus and compressive strength of SPC showed an increasing trend, and the compressive modulus of 60%-SPC was slightly lower than that of 40%-SPC. There were significant differences in compressive modulus and compressive strength between the materials (P<0.05). In vitro simulated fluid degradation experiments showed that the mass loss of the three types of SPC after 180 days of degradation was within 5%, with the highest mass loss observed in 60%-SPC. The differences in mass loss between the materials were significant (P<0.05). As the silk content increased, the static water contact angle of each material gradually decreased, and all could promote the proliferation of MC3T3-E1 cells. The subcutaneous degradation experiment in rats showed that 20%-SPC began to degrade at 30 days after implantation, and material degradation and vascularization were significant at 180 days, which was in sharp contrast to PCL. Conclusion SPC has the mechanical and hydrophilic properties that are compatible with bone tissue. It maintains its mechanical strength for a long time in a simulated body fluid environment in vitro, and achieves dynamic synchronization of material degradation, tissue regeneration, and vascularization through the body’s immune regulation mechanism in vivo. It is expected to provide a new type of implant material for clinical bone repair.
Objective To select levorotatory polylactic acid (PLLA) and polycaprolactone (PCL) as the main materials, use electrostatic spinning and ultrasonic broaching processing technique to prepare a similar to natural vascular diameter gradient structure of large diameter artificial blood vessels, and evaluate its potential applications. Methods Using PLLA and PCL as raw materials, through the electrospinning process, using core shafts of different diameters as collection devices, artificial vascular materials with a natural-like structure were constructed. Using end to end anastomosis method to experimental pig thoracic descending aorta replacement of artificial blood vessels. Results Computed tomography angiography (CTA) results showed that the artificial vascular graft was patent at 1 week and 6 weeks after operation. Animal experimental pathology examination revealed, artificial blood vessels unobstructed, the lining of endothelial cells, and elastic fiber, roughly three layer structure formed similar natural aorta. Artificial blood vessel wall visible elastic fibers, elastic fibers and collagen fibers with natural blood vessels distribution was similar. Immunohistochemical examination showed that the artificial blood vessels had a strong immune response to ERG staining, Actin staining, and Vementin staining. Scanning electron microscopy showed that endothelial cells were formed in the inner layer of the artificial blood vessel. Conclusion PLLA and photo as raw material, the use of electrostatic spinning and ultrasonic reaming technology preparation of large diameter artificial blood vessels, imitation of natural structure may have potential good flow resistance, good endothelial and may have induced in-situ natural function of angiogenesis.