Objective To explore the advance in physical materials,chemical matrix, and biological seed cells for fabricating artificial nerve. Methods Recent literature relevant to artificial nerve, especially the achievement in physical material, chemical matrix and biological seed cells for fabricating artificial nerve, were extensively reviewed. Results Polymers of polylactic acid or polyglycolic acid and their polymer, polymer of hyaluronic acid and glut-aldehyde, polymer of polyacrylonitrile and polyvinylchloride were artificial nerve materials with the properties of good biocompatibility and biodegradation. A conduit with multichannel and high percentage of pores was beneficial to the regeneration of nerve. The activated Schwann cells were excellent seeds of artificial nerve. A suitable chemical matrix, such as laminin and alginate, could promote the regeneration of nerve. Conclusion The successful fabrication of artificial nerve lies in the advance in the mechanism of nerve regeneration and physical material, chemical matrix and biological seed cells.
OBJECTIVE To investigate the methods to fabricate repair materials of tissue engineered peripheral nerve with bioactivity of Schwann cells (SC). METHODS 1. The materials were made by dry-wet spinning process to fabricate PLA hollow fiber canal with external diameter of 2.3 mm, internal diameter of 1.9 mm, thickness of 0.4 mm, pore size of 20 to 40 microns, pore ratio of 70% and non-spinning fiber net with pore size of 100 to 200 microns, pore ratio of 85%. 2. SC were implanted into excellular matrix (ECM) gel to observe the growth of SC. 3. SC/ECM complex were implanted into non-spinning PLA fiber net to observe the growth of SC. 4. SC, SC/ECM and SC/ECM/PLA were implanted into PLA hollow fiber canal to bridge 10 mm defect of rat sciatic nerve. RESULTS 1. SC were recovered bipolar shape at 1 day after implantation, and could be survived 14 days in ECM gel. 2. After SC/ECM complex was implanted into PLA net, most of SC were retained in the pore of PLA net with the formation of ECM gel. SC could be adhered and grown on PLA fiber. 3. Most of SC in ECM gel could be survived to 21 days after transplantation. Survival cell numbers of SC/ECM and SC/ECM/PLA groups were obviously higher than SC suspension group. CONCLUSION Non-spinning PLA porous biodegradable materials with ECM is benefit for SC to be adhered and grown.
Objective To explore a green route for the fabrication of thermo-sensitive chitosan nerve conduits, improve the mechanical properties and decrease the degradation rate of the chitosan nerve conduits. Methods Taking advantage of the ionic specific effect of the thermo-sensitive chitosan, the strengthened chitosan nerve conduits were obtained by immersing the gel-casted conduits in salt solution for ion-induced phase transition, and rinsing, lyophilization, and 60Co sterilization afterwards. The nerve conduits after immersing in NaCl solutions for 0, 4, 12, 24, 36, 48, and 72 hours were obtained and characterized the general observation, diameters and mechanical properties. According to the above results, the optimal sample was chosen and characterized the microstructure, degradation properties, and cytocompatibility. The left sciatic nerve defect 15 mm in length was made in 20 male Sprague Dawley rats. The autologous nerves (control group, n=10) and the nerve conduits (experimental group, n=10) were used to repair the defects. At 8 weeks after operation, the compound muscle action potential (CMAP) was measured. The regenerated nerves were investigated by gross observation and toluidine blue staining. The gastrocnemius muscle was observed by HE staining. Results With the increased ionic phase transition time, the color of the conduit was gradually deepened and the diameter was gradually decreased, which showed no difference during 12 hours. The tensile strength of the nerve conduit was increased gradually. The ultimate tensile strength showed significant difference between the 48 hours and 12, 24, and 36 hours groups (P<0.05), and no significant difference between the 48 hours and 72 hours groups (P>0.05). As a result, the nerve conduit after ion-induced phase transition for 48 hours was chosen for further study. The scanning electron microscope (SEM) images showed that the nerve conduit had a uniform porous structure. The degradation rate of the the nerve conduit after ion-induced phase transition for 48 hours was significantly decreased as compared with that of the conduit without ion-induced phase transition. The nerve conduit could support the attachment and proliferation of rat Schwann cells on the inner surface. The animal experiments showed that at 8 weeks after operation, the CMAPs of the experimental and control groups were (3.5±0.9) and (4.3±1.1) m/V, respectively, which showed no significant difference between the two groups (P<0.05), and were significantly lower than that of the contralateral site ［(45.6±5.6 m/V), P>0.05］. The nerve conduit of the experimental group could repair the nerve defect. There was no significant difference between the experimental and control groups in terms of the histomorphology of the regenerated nerve fibers and the gastrocnemius muscle. Conclusion The green route for the fabrication of thermo-sensitive chitosan nerve conduits is free of any toxic reagents, and has simple steps, which is beneficial to the industrial transformation of the chitosan nerve conduit products. The prepared chitosan nerve conduit can be applied to rat peripheral nerve defect repair and nerve tissue engineering.
Objective To study the result of using nerve conduit coated with chitin and filled with a guide-fiber to repair peripheral nerve defect. Methods Twenty-four female adult SD rats were made the model of 14 mm-gap on bilateral sciatic nerve under sterile condition. The rats were randomly divided into 4 groups(n=6),group A: polymer polyglycolic-lactic acid(PGLA) nerve conduit coated with chitin and filled with a guide-fiber as experimental group to repair 14 mm gap of rat sciatic nerve；group B: PGLA nerve conduit coated with chitin； group C: PGLA nerve conduit； group D: autograft (control group). The repair result was evaluated by normal observation, EMG testing and S-100 histological immunostaining analysis 4 and 12 weeks after operation.Results Four weeks after the operation，there were new regenerated immature fibers in groups A,B and C, 12 weeks after the operation, the regenerated nerve fibers were seen to have bridged the gap. There were myelinated fibers equably distributed and rarely newgenerated nerve fibers in distal parts of group D. The repair result of PGLA nerve conduit coated with a chitin and filled with guide-fiber was better than that of groups B and C（Plt;0.05）. There was significant difference of nerve fiber diameter，thickness of myelin sheath and fiber density in group D from those in groups A, B and C（Plt;0.05），but there were degenerative changes such as vacuoles insheaths and myelin separation in proximal and few new regenerated nerve fibers in distal parts of group D. Conclusion PGLA nerve conduit coated with chitin and filled with a guide-fiber offers a possible substitute for the repair of peripheral nerve defect.
ObjectiveTo evaluate the clinical outcome of valved homograft conduits (VHC) used for right ventricular outflow tract (RVOT) reconstruction in Fuwai Hospital in recent 13 years, and explore the factors influencing the long-term durability of VHC. MethodsClinical data of patients using VHC for RVOT reconstruction in Fuwai Hospital from November 2007 to October 2020 were retrospectively analyzed. The Kaplan-Meier survival curve was used to evaluate survival, VHC reintervention and VHC dysfunction. Cox proportional risk regression model was used to analyze the risk factors for VHC dysfunction. ResultsFinally 251 patients were enrolled, including 145 males and 106 females. The median age at surgery was 6.0 (0.3-67.0) years. Early death occurred in 5 (2.0%) patients. The follow-up was available for 239 (95.2%) patients, with the follow-up time of 0.3-160.0 (61.3±45.4) months. Five patients died during the follow-up, and the 1-year, 6-year, and 13-year survival rates were 96.6%, 95.5% and 95.5%, respectively. Eight patients received VHC reintervention during the follow-up, and freedom rates from VHC reintervention were 100.0%, 97.1% and 82.4% at 1 year, 6 years and 13 years, respectively. A total of 226 patients were followed up by echocardiography after discharge, with the follow-up time of 0.2-138.0 (48.5±40.5) months. During the follow-up, 46 (20.4%) patients developed VHC dysfunction, and freedom rates from VHC dysfunction at 1 year, 5 years, and 10 years were 92.6%, 79.6% and 59.3%, respectively. Univariate Cox regression analysis showed that age<6 years and VHC diameter<19 mm were risk factors for VHC dysfunction (P=0.029, 0.026), but multivariate regression analysis only indicated that age<6 years was an independent risk factor for VHC dysfunction (P=0.034). ConclusionThe early and late outcomes of VHC used for RVOT reconstruction are satisfactory, and the long-term durability of VHC is also optimal. In addition, age<6 years is an independent risk factor for VHC dysfunction.
ObjectiveTo investigate the effect of electrospun chitosan/polylactic acid (ch/PLA) nerve conduit for repairing peripheral nerve defect in rats. MethodsNerve conducts loaded with ch/PLA was made by the way of electrospun. The mechanical property, hydrophility, biocompatibility were tested, and the scanning electron microscope was used to observe the ultrastructure. The same experiments were also performed on pure PLA nerve conducts as a comparison. Then, 54 Sprague Dawley rats were divided into 3 groups randomly, 18 rats in each group. Firstly, the 10 mm defects in the right sciatic nerves were made in the rats and were respectively repaired with ch/PLA (group A), autografts (group B), and no implant (group C). At 4, 8, and 12 weeks after operation, general observations, sciatic functional index (SFI), electrophysiological evaluation, wet weight of gastrocnemius and soleus muscles, histological examination, immunohistological analysis, and transmission electron microscopy were performed to evaluate the effects. ResultsCompared with pure PLA nerve conducts, the addition of chitosan could improve the mechanical property, hydrophility, biocompatibility, and ultrastructure of the nerve conducts. At 4 weeks postoperatively, the regenerated nerve bridged the nerve defect in group A. The SFI improved gradually in both group A and group B, showing no significant difference (P>0.05). Compound muscle action potentials and nerve conduction velocity could be detected in both group A and group B at 8 and 12 weeks after operation, and significant improvements were shown in both groups (P<0.05). The wet weight and myocyte cross section of gastrocnemius and soleus muscles showed no significant difference between group A and group B (P>0.05), but there was significant difference when compared with group C (P<0.05) at 12 weeks postoperatively. Immunohistological analysis revealed that S-100 positive Schwann cells migrated in both group A and group B, and axon also regenerated by immunohistological staining for growth associated protein 43 and neurofilaments 160. Transmission electron microscopy showed no significant difference in the diameter of nerve fiber between group A and group B (P>0.05), but the thickness of myelin sheath in group A was significantly larger than that in group B (P<0.05). ConclusionThe electrospun ch/PLA nerve conduits can effectively promote the peripheral nerve regeneration, and may promise an alternative to nerve autograft for repairing peripheral nerve defect.
Objective To investigate the surgery experience of modified intra/extracardiac conduit total cavopulmonary connection (TCPC). Methods We retrospectively analyzed clinical data of 47 patients of complex congenital heart disease undergoing intra/extracardiac conduit total cavopulmonary connection in our hospital between January 2008 and December 2015. There were 29 males and 18 females with a median age of 7 years (range 4 to 9 years) and median body weight of 22 kg (range 14 to 38 kg). The heart echocardiography and cardiac imaging confirmed diagnosis suitable for TCPC surgery. Results There was no early death in the whole group. The mean pulmonary arterial pressure was 16 (12–20) mm Hg and the ventilation time was 14 (7–97) h. The main complications were intractable pleural effusion in 7 patients, low cardiac output syndrome in 3 patients, repeated supraventricular tachycardia in 1 patient. All the patients recovered after treatment. At the end of discharge, the percutaneous oxygen saturation was 85%–96% (92.6%±3.3%). The echocardiography showed the conduit pressure was 0–2 mm Hg. Patients were followed up for 1 to 7 years. Three patients were lost. One patient had intestinal nutrition loss, receving repeated pleural effusion, the treatment was ineffective, died after 4 years. Four patients of repeated pleural effusion improved after treatment. One patient repeated attacks supraventricular tachycardia within 1 year, controlled by amiodaronum, already stopped about 28 months. No recurrence occurred. All survivors were in New York Heart Association (NYHA) functional class Ⅰ or Ⅱ, with good activity tolerance. Conclusion The modified intra/extracardiac conduit TCPC combines the advantages of both the lateral tunnel and the extracardiac conduit. The operation is simple, used in the treatment of complex congenital heart disease. The short-term and mid-term results are encouraging.
Objective Comparing postoperative change of blood gas and hemodynamic status in patients underwent a right ventricletopulmonary artery (RVPA) conduit or a modified BlalockTaussig (mBT) shunt for pulmonary atresia with ventricular septal defect and without major arterial pulmonary collaterals (MAPCAs), to affirm the effect on oxygen supply /demand with different procedure. Methods From July 2006 to October 2007, 38 patients with pulmonary atresia and ventricular septal defect without MAPCAs were divided into two groups according to different procedures: RVPA group (n=25) and mBT group (n=13).Perioperative mortality, blood gas and hemodynamic data during postoperative 48 hours, including heart rate, blood pressure, systemic oxygen saturation, mixed venous oxygen saturation, oxygen excess factor, inotropic score were compared in both groups. Results The difference in the mortality between RVPA group (4.0％，1/25) and mBT group （7.7％，1/13) showed no statistical significance（Pgt;0.05）. The total of 33 patients were followed up, the followup time was from 6 to 18 months.11 patients (4 patients in mBT group, 7 patients in RVPA group) underwent corrected procedures during 9 to 18 months after palliative procedures, one case died of elevated pulmonary vascular resistance and right ventricle failure. The mixed venous oxygen saturation at 24h and 48h after surgery were higher than that at 6h after surgery (Plt;0.01) both in RVPA group and mBT group. The systolic blood pressures at 6h, 24h, 48h after surgery in RVPA group were lower than those in mBT group (P=0.048，0.043， 0.045)，the mean systemic blood pressures in RVPA group were higher than those in mBT group (P=0.048, 0.046, 0.049),the diastolic blood pressures in RVPA group were higher than those in mBT group (P=0.038, 0.034, 0.040)， the inotropic scores in RVPA group were lower than those in mBT group (P=0.035， 0.032，0.047). Conclusion The blood pressures and inotropic scores are found significantly different in RVPA conduit and mBT procedures, while postoperative systemic oxygen delivery areequivalent. Both RVPA and mBT patients decline to nadir in hemodynamic status at 6 h after surgery.
ObjectiveTo compare the long-term durability of valved homograft conduit (VHC) in patients with Ross and non-Ross right ventricular outflow tract (RVOT) reconstruction. MethodsPatients who underwent RVOT reconstruction using VHC in Fuwai Hospital from January 2008 to October 2020 were retrospectively included. Patients who received Ross RVOT reconstruction were allocated to a Ross group and patients who received non-Ross RVOT reconstruction were allocated to a non-Ross group. The survival and reintervention-free rates of the two groups were evaluated with the Kaplan-Meier survival curve and log-rank test. The propensity score matching analysis was performed on the patients who completed ultrasound follow-up in the two groups, and the VHC dysfunction-free rate was compared between the two groups. ResultsA total of 243 patients were enrolled, including 142 males and 101 females, with a median age of 6 years (4 months to 56 years). There were 77 patients in the ROSS group and 166 patients (168 operations) in the non-ROSS group. The cardiopulmonary bypass time in the Ross group was shorter than that in the non-Ross group (175.4±45.6 min vs. 200.1±83.5 min, P=0.003). Five patients in the non-Ross group died early after the operation. The follow-up was available in 231 patients (93.1%), with the average follow-up time of 61.7±44.4 months. During the follow-up, 5 patients in the non-Ross group died. The 12-year survival rate was 100.0% in the Ross group and 93.2% in the non-Ross group (log-rank, P=0.026). In addition, 1 patient in the Ross group and 7 patients in the non-Ross group received VHC reintervention. There was no significant difference in the reintervention-free rate between the two groups (log-rank, P=0.096). Among the 73 patients in the Ross group and 147 patients in non-Ross group who were followed up by ultrasound after discharge, 45 patients (20.5%) developed VHC dysfunction. Before matching, the long-term durability of VHC in the Ross group was better than that in non-Ross group (10-year VHC dysfunction-free rate: 66.6% vs. 37.1%, log-rank, P=0.025). After the propensity score matching, 64 patients included in each group, and there was no statistical difference in the long-term durability of VHC between the two groups (10-year VHC dysfunction-free rate: 76.3% vs. 43.0%, log-rank, P=0.065). In the subgroup analysis, the 10-year VHC dysfunction-free rate in the Ross group was higher than that in the non-Ross group (71.0% vs. 20.0%, log-rank, P=0.032) among patients aged<6 years at surgery. However, there was no significant difference in the 10-year VHC dysfunction-free rate between the two groups (53.7% vs. 56.7%, log-rank, P=0.218) among patients aged ≥6 years at surgery. ConclusionAfter the propensity score matching analysis, the long-term durability of VHC has no significant difference between the Ross group and non-Ross group. The long-term durability of VHC after Ross surgery is superior to that of non-Ross surgery in patients aged<6 years at surgery.
ObjectiveTo summarize clinical experience and outcomes of extracardiac conduit total cavopulmonary connection (TCPC)for surgical treatment of complex congenital heart diseases. MethodsClinical data of 52 patients who underwent extracardiac conduit TCPC from September 2006 to December 2012 in Department of Cardiac Surgery, Guangzhou General Hospital of Guangzhou Military Command were retrospectively analyzed. There were 12 patients who received one-stage extracardiac conduit TCPC. There were 40 patients who received two-staged extracardiac conduit TCPC after bidirectional Glenn procedure. Clinical data of all the patients were analyzed. Mortality, morbidity, length of hospital stay and intensive care unit (ICU)stay, mechanical ventilation time, change of arterial oxygen saturation (SaO2)were compared between the 2 groups. ResultsTwo patients (3.8%)died postoperatively including 1 patient with severe low cardiac output syndrome and another patient with multiple organ dysfunction syndrome. Fifty patients were discharged successfully. Mechanical ventilation time, length of ICU stay and hospital stay of the 40 patients who received two-stage extracardiac conduit TCPC were significantly shorter than those of the 12 patients who received one-stage extracardiac conduit TCPC. There was no statistical difference in postoperative morbidity, SaO2 (two-staged vs. one-staged:93%±3% vs. 94%±3%)or mortality (two-staged vs. one-staged:2.5% vs.8.3%)between the 2 groups (P > 0.05). Forty-five patients (90%)were followed up for 6-52 months, and there was no death during follow-up. At 3 months after TCPC, all the patients had heart function of class I or II, and echocardiography showed patent cavopulmonary anastomosis. ConclusionExtracardiac conduit TCPC is a simple procedure, can produce more physiological hemodynamic results, and can be performed for patients who cannot undergo biventricle procedure. Compared with one-stage extracardiac conduit TCPC, two-staged extracardiac conduit TCPC has wider surgical indications, can produce better postoperative recovery, and is easier to perform.