Months Of Implantation Research Articles

Mechanical properties of de-epithelialized tracheal allografts.

BackgroundMany studies have shown that mucosa-treated tracheas can be used for allotransplantation without the use of immunosuppressants. However, no literature has reported whether the transplanted trachea has normal biomechanics. In this study, fresh dog trachea was used as a control to determine the mechanical properties of allograft trachea after mucous membrane removal.MethodsCervical tracheas (~10 cm in length, consisting of the cartilage rings down to the tracheal carina) and the surrounding connective tissues were removed from 20 mixed-breed dogs and then divided into 4 groups with 5 samples in each group. The groups were defined as follows: group A, fresh canine tracheas without any treatment; group B, canine tracheas after sodium dodecyl sulphate (SDS) de-epithelialization; group C, canine tracheas implanted into the dorsal fascia of beagle dogs for 1 month after SDS de-epithelialization; group D, canine tracheas implanted into the dorsal fascia of beagle dogs for 6 months after SDS de-epithelialization. All heterotopically implanted beagle dogs were free of any immunosuppressive treatment. Uniaxial tensile (n=20) and compressive (n=20) experiments were performed on the 4 groups of trachea using a universal testing machine; the tensile load was recorded at 150% of the original tracheal length (50% displacement), and the compressive load was recorded at 50% of the initial anteroposterior diameter (50% displacement). The average difference in tensile and compressive loads between groups was compared by analysis of variance.ResultsNo significant difference was found in the mean compressive strength among groups (group A =2.38±0.87 N, group B =3.33±1.03 N, group C =5.39±2.44 N, group D =3.04±2.12 N; P=0.07 for all groups). The mean tensile strength of group C was 9.68±0.86 N, resulting in a significant difference in tensile strength compared to group A (22.51±3.91 N) and B (24.24±7.46 N) (P<0.001). No significant difference in tensile strength was observed among groups A, B, and D.ConclusionsThe de-epithelialized trachea showed no significant change in mechanical properties after 6 months of implantation.

Correction of coronal plane deformities around knee in children with two-hole tension band plates.

Objectives This study aims to present the 10-year results and complications of two-hole tension band plate hemiepiphysiodesis for coronal deformities around knee in a large population from a single center.Patients and methods Seventy-seven patients (46 boys, 31 girls; mean age 93±36 months; range, 22 to 181 months) who underwent temporary hemiepiphysiodesis around knee between January 2009 and January 2019 with two-hole tension band plates were retrospectively evaluated. Improvement of joint orientation angles and mechanical axis deviations, deformity correction rates, etiology groups, and complications were noted.Results A total of 166 bone segments (93 femurs, 73 tibias) were included in the study. Mean follow-up duration after the implantation was 36±17 (range, 12 to 88) months. Plates were removed at mean 18±8 (range, 7 to 47) months of implantation. Of the bone segments, 95.2% (n=158) responded successfully to the plates. Mean correction rate of mechanical lateral distal femoral angle in femoral valgum deformity was 0.94±0.43° (range, 0.17 to 2.22)/month and mean correction rate of mechanical medial proximal tibial angle in tibial valgum deformity was 0.62±0.36° (range, 0.11 to 1.55)/month. Mean correction rate of mechanical lateral distal femoral angle in femoral varum deformity was 1.3±0.8° (range, 0.48 to 2.92)/month and mean correction rate of mechanical medial proximal tibial angle in tibial varum deformity was 0.94±0.49° (range, 0.26 to 1.67)/month. The most common complication observed was rebound deformity seen in 41.2% (n=70) of the bone segments. Nine bone segments had persistent hemiepiphysiodesis despite plate removal. Four screw breakages (three metaphysial and one epiphysial) were observed.Conclusion Two-hole tension band plate hemiepiphysiodesis appears to be an effective and safe method for the correction of coronal deformities around knee.

Degradation Phenomena on “Homemade” Explanted Aortic Textile Endografts

ObjectiveIn the 1990s, the concept of “homemade” endografts (EGs) using commercially available materials was proposed in clinical practice for endovascular abdominal aortic repair (EVAR). The aim of this study was to analyse the ageing phenomena of these EGs in light of explant analyses.MethodsThe study focused on five explanted homemade EGs collected from 2012 to 2014. The explants were assessed in accordance with the ISO 9001/13485 certified standard protocol, which included naked eye evaluation, organic remnant cleaning, and microscopic and endoscopic examinations and analysis (magnification range from 20% to 200%). The observations report followed a classification based on 12 features assessing the fabric cover, the stitch filament, and the stents.ResultsThe reasons for explantation were type 1 endoleak in three cases and aneurysm sac growth in two. The implantation duration ranged from 56 to 202 months. Sixty three per cent of the fabric surface lesions (holes and tears) were related to abrasion between the fabric and the stents. Up to 33% of the knots used to connect adjacent stents were broken on one EG. Other defects including running suture rupture and stent corrosion were also observed. The overall hole cumulated surface ranged from 0.377 mm2 (56 month of implantation) up to 3.21 mm2 (78 month of implantation).ConclusionIn this study, various ageing phenomena on homemade textile EGs were identified and classified. The main damaging mechanisms were related to abrasion stress leading to tears and holes in the fabric, stitch ruptures, and detachment of stent segments responsible for serious EG deformations and further degradation.

Tissue-engineered patch modified by vascular endothelial growth factor for reconstruction of vascular wall

Background. Commercially available synthetic and animal-derived vascular patches used in patch angioplasty during carotid endarterectomy have several disadvantages, such as postoperative thrombosis or occlusion and restenosis. This problem may be resolved by the development of biologically active materials that are biodegradable and can stimulate tissue regeneration.Aim. To evaluate the properties and efficacy of a biodegradable patch based on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(ε-caprolactone) (PCL) into which vascular endothelial growth factor (VEGF) is incorporated, in comparison with unmodified PHBV/PCL and commercial vascular patches.Methods. Porous patches were fabricated by emulsion electrospinning from a mixture of PHBV and PCL, into which VEGF was incorporated. The morphological and mechanical properties of these patches were tested, and they were implanted into the wall of rat abdominal aortas for 1, 3, 6 and 12 months. Histological and immunofluorescence examinations were performed to evaluate endothelisation, cellular composition and calcification.Results. PHBV / PCL patches with VEGF had a highly porous structure and demonstrated tensile strength similar to that of the aorta in rats and the internal thoracic artery in humans. After 3 months of implantation, an endothelial monolayer was formed on the inner surface of these patches. The patches were populated by cells that secreted the extracellular matrix faster than did cells of patches from the xenopericardium. Remodelling with PHBV / PCL patches was not accompanied by chronic inflammation; in contrast, inflammation was observed with long-term implantation of unmodified PHBV / PCL samples.Conclusion. VEGF incorporated into biodegradable PHBV / PCL patches stimulated their endothelisation, increased their biocompatibility and promoted remodelling and formation of the components of the blood vessel. PHBV / PCL / VEGF patches thus have a high potential for use in tissue engineering of the vascular wall. Received 2 June 2020. Revised 27 June 2020. Accepted 16 July 2020. Funding: This study was supported by the Complex Program of Basic Research under the Siberian Branch of the Russian Academy of Sciences within the Basic Research Topic of Research Institute for Complex Issues of Cardiovascular Diseases № 0546-2019-0002 “Pathogenetic basis for the development of cardiovascular implants from biocompatible materials using patient-oriented approach, mathematical modeling, tissue engineering, and genomic predictors”. Conflict of interest: Authors declare no conflict of interest. Author contributionsConception and study design: V.V. Sevostianova, A.V. Mironov, L.V. Antonova, R.S. Tarasov, L.S. BarbarashData collection and analysis: V.V. Sevostianova, A.V. Mironov, L.V. Antonova, E.O. Krivkina, V.G. Matveeva, E.A. Velikanova, T.V. GlushkovaStatistical analysis: V.V. Sevostianova, T.V. GlushkovaDrafting the article: V.V. Sevostianova, A.V. Mironov Critical revision of the article: L.V. Antonova, R.S. Tarasov, L.S. BarbarashFinal approval of the version to be published: V.V. Sevostianova, A.V. Mironov, L.V. Antonova, E.O. Krivkina, V.G. Matveeva, E.A. Velikanova, R.S. Tarasov, T.V. Glushkova, L.S. Barbarash

Biosafety evaluation of culture-expanded human chondrocytes with growth factor cocktail: a preclinical study

The scarcity of chondrocytes is a major challenge for cartilage tissue engineering. Monolayer expansion is necessary to amplify the limited number of chondrocytes needed for clinical application. Growth factors are often added to improve monolayer culture conditions, promoting proliferation, and enhancing chondrogenesis. Limited knowledge on the biosafety of the cell products manipulated with growth factors in culture has driven this study to evaluate the impact of growth factor cocktail supplements in chondrocyte culture medium on chondrocyte genetic stability and tumorigenicity. The growth factors were basic fibroblast growth factor (b-FGF), transforming growth factor β2 (TGF β2), insulin-like growth factor 1 (IGF-1), insulin-transferrin-selenium (ITS), and platelet-derived growth factor (PD-GF). Nasal septal chondrocytes cultured in growth factor cocktail exhibited a significantly high proliferative capacity. Comet assay revealed no significant DNA damage. Flow cytometry showed chondrocytes were mostly at G0-G1 phase, exhibiting normal cell cycle profile with no aneuploidy. We observed a decreased tumour suppressor genes’ expression (p53, p21, pRB) and no TP53 mutations or tumour formation after 6 months of implantation in nude mice. Our data suggest growth factor cocktail has a low risk of inducing genotoxic and tumorigenic effects on chondrocytes up to passage 6 with 16.6 population doublings. This preclinical tumorigenicity and genetic instability evaluation is crucial for further clinical works.

In Situ Remodeling Overrules Bioinspired Scaffold Architecture of Supramolecular Elastomeric Tissue-Engineered Heart Valves

In situ tissue engineering that uses resorbable synthetic heart valve scaffolds is an affordable and practical approach for heart valve replacement; therefore, it is attractive for clinical use. This study showed no consistent collagen organization in the predefined direction of electrospun scaffolds made from a resorbable supramolecular elastomer with random or circumferentially aligned fibers, after 12months of implantation in sheep. These unexpected findings and the observed intervalvular variability highlight the need for a mechanistic understanding of the long-term in situ remodeling processes in large animal models to improve predictability of outcome toward robust and safe clinical application.

Comparative Osteointegration Testing of Titanium Implants in Relation to Gender After One Month of Implantation in Rabbit Femur

The biologic material used in this study is represented by 6 rabbits, 3 males and 3 females, aged 11 months and having an average weight of 4 kg. After general anaesthesia was performed, 2 mm diameter titanium implants were surgically inserted in the femur. Postoperative care of the animals included daily observation. After 4 weeks the animals were euthanized according to the guidelines. The femurs were collected along with the implants and processed for histological examination. The samples were placed in Stieve mixture for fixation, dehydrated with ethylic alcohol, clarified with 1-Butanol, and followed by paraffin embedding. 5 micrometers sections were cut using a microtome, and then stained using the Goldner trichrome staining method and were examined using an Olympus BX41 microscope with an attached digital camera for image capturing. In all animals, the implant was well tolerated by the bone and soft tissue implantation bed. The osteointegration process took place through bone formation around the implant, with variations in thickness and structure throughout the bone-implant interface. Except for the accelerated speed of osteointegration steps, observed in males, the osteointegration process follows certain stages and no gender related differences. The rapid progress of osteointegration in males resulted in a faster process in this gender compared to females. This aspect is clinically relevant for the appropriate evaluation of waiting periods from implant placement to prosthetic mounting, which according to this study is different in males and females.

Cyborg Vessel

Cyborg Vessel

Non-invasive hemodynamic determination of patient-specific optimal pacing mode in cardiac resynchronization therapy.

Cardiac resynchronization therapy (CRT) devices have multiple programmable pacing parameters. The purpose of this study was to determine the best pacing mode, i.e., associated with the greatest acute hemodynamic response, in each patient. Patients in sinus rhythm and intact atrioventricular conduction were included within 3 months of implantation of devices featuring SyncAV and multipoint pacing (MPP) algorithms. The effect of nominal biventricular pacing using the latest activated electrode (BiV-Late), optimized atrioventricular delay (AVD), nominal and optimized SyncAV, and anatomical MPP was determined by non-invasive measurement of systolic blood pressure (SBP). CRT response was defined as SBP increase > 10% relative to baseline. Thirty patients with left bundle branch block (LBBB) were included. BiV-Late increased SBP compared to intrinsic rhythm (128 ± 21 mmHg vs. 121 ± 22 mmHg, p = 0.0002). The best pacing mode further increased SBP to 140 ± 19 mmHg (p < 0.0001 vs. BiV-Late). The proportion of CRT responders increased from 40% with BiV-Late to 80% with the best pacing mode (p = 0.0005). Compared to BiV-Late, optimized AVD and optimized SyncAV increased SBP (to 134 ± 21 mmHg, p = 0.004, and 133 ± 20 mmHg, p = 0.0003, respectively), but nominal SyncAV and MPP did not. The best pacing mode was variable between patients and was different from nominal BiV-Late in 28 (93%) patients. Optimized AVD was the most frequent best mode, in 14 (47%) patients. In patients with LBBB, the best pacing mode was patient-specific and doubled the magnitude of acute hemodynamic response and the proportion of acute CRT responders compared to nominal BiV-Late pacing. ClinicalTrials.gov : NCT03779802.

Electrocardiographic Model to Predict Cardiac Resynchronization Therapy Response among Chronic Heart Failure Patients

Background: Despite contemporary restrictive clinical and electrocardiographic selection criteria, up to one-third of chronic heart failure patients with implanted cardiac resynchronization therapy (CRT) are non-responders. Previous studies reported that some electrocardiographic patterns, such as the longer the intrinsicoid deflection (ID) in lead I, the higher the R wave amplitude in V₆, and other patterns may be helpful for CRT response prediction. Objective: To establish a simplified model using electrocardiographic parameters as predictors of CRT response among chronic heart failure patients. Materials and Methods: Eighty chronic heart failure patients meeting the current guideline recommendation for CRT implantation were enrolled in the present retrospective cohort study. The patients’ clinical and electrocardiographic parameters at the time of CRT implantation and during follow-up were analyzed. The response to CRT was evaluated after six months of implantation, defined as a decrease in the left ventricular end systolic volume (LVESV) of 15% or more or an increase in the left ventricular ejection fraction (LVEF) of 10% or more. Results: During a median follow-up period of 34 months, there were 45 (56.3%) responders. In multivariate analysis, the independent predictors for CRT response were the greater the reduction of the QRS complex duration after implantation (QRS post – QRS pre), the higher the time to ID in the lead I/QRS ratio (ID I/QRS), and the higher the difference in the amplitude of the R and S waves in lead V₁ and V₆ [(S1+R6) – (S6+R1)] (QRS post – QRS pre: adjusted odds ratio [OR] 0.97, 95% CI 0.94 to 0.99, p=0.004; ID I/QRS: OR 18.65, 95% CI 1.02 to 342.64, p=0.049; (S1+R6) – (S6+R1): OR 1.1, 95% CI 1.04 to 1.17, p=0.002). The new equation for calculating the predictive CRT response model, generated from multiple logistic regression analysis, was –3.414 – 0.035(QRS post – QRS pre) + 2.926(ID I/QRS) + 0.097[(S1+R6) – (S6+R1)]. The area under the receiver operating characteristic (ROC) curve for the new model for predicting CRT response was 0.853 (95% CI 0.767 to 0.939). A model score of more than 0.3 showed a sensitivity of 85.7% and specificity of 80% for the prediction of CRT response. Conclusion: The new electrocardiographic model achieved a high sensitivity and specificity for the prediction of CRT response among chronic heart failure patients, who met the current guideline recommendation for CRT implantation. Keywords: Cardiac resynchronization therapy, Electrocardiography, Heart failure, Responders, Model

Predictors of increase in pacing threshold after transcatheter pacing system implantation due to micro-dislodgement.

Achieving a favorable pacing threshold with a Micra transcatheter pacing system (Micra-TPS) is needed to reduce battery depletion. In some cases, the threshold increases shortly after the device is implanted, and a higher pacing threshold may be required. This study aims to identify the causes and predictors of the increase in pacing threshold observed shortly after Micra-TPS implantation. The study included 64 consecutive patients who underwent Micra-TPS implantation between 2017 and 2020. The patients were divided into two groups depending on their pacing threshold: the increased pacing threshold (IPT) group (threshold increased by ≥0.5 V/0.24 ms within 1 month of implantation) and the stable pacing threshold (SPT) group. Excluding four patients who could not be followed up, of the 60 remaining patients, nine (15%) were in the IPT group and 51 (85%) were in the SPT group. The IPT group had significantly lower implant impedance values and higher implant thresholds than the SPT group (582 ± 59vs 755 ± 167 Ω [P<.001] and 1.29 ± 0.87vs 0.71 ± 0.40 V/0.24 ms [P=.014]). Implant impedance and threshold may serve as predictors of a threshold increase after implantation (area under the curve: 0.737-0.943 and 0.586-0.926, respectively). An IPT was noted shortly after Micra-TPS implantation owing to micro-dislodgement because of insufficient anchoring of the device to the myocardium. Impedance>660 Ω and threshold<1.0 V/0.24 ms may predict an increase in pacing threshold.

Safety and performance of everolimus-eluting stents comprising of biodegradable polymers with ultrathin stent platforms.

The registry investigated clinical outcomes after 12 months of implantation of ultra-thin strut (60 µm) biodegradable polymer-coated Tetrilimus everolimus-eluting stents (EES; Sahajanand Medical Technologies Pvt. Ltd., Surat, India) in patients with atherosclerotic coronary lesions. Additionally, sub-group analysis was performed to evaluate outcomes of ultra-long (44/48 mm) Tetrilimus EES in patients with long lesions. This was an observational, single-center, single-arm and investigator-initiated retrospective registry. In this all-comers registry, patients who underwent implantation of Tetrilimus EES for treatment of coronary artery disease during routine clinical practice between February-2016 and August-2016 at tertiary care center of India were included. Primary endpoint was occurrence of any major adverse cardiac event (MACE) up to 12 months' follow-up. MACE was a composite of cardiac death, myocardial infarction (MI), and target lesion revascularization (TLR). Similar endpoints were observed in sub-group patients. Total 766 stents were implanted to treat 695 lesions in 558 patients. Of treated lesions, 11.4% lesions were type B2 and 78.3% were type C lesions. In sub-group analysis of 143 patients, a total of 155 long coronary lesions were intervened successfully with only one stent been implanted per lesion. At 12 months' follow-up, four (0.7%) cases of cardiac death, eight (1.4%) of MI, and two (0.4%) of TLR were reported, resulting in a 2.5% rate of MACE. The MACE rate was 2.8% in sub-group patients. Twelve months' clinical data demonstrated favorable safety and excellent performance of Tetrilimus EES in high-risk patients and complex coronary lesions in routine clinical practice and also in patients with ultra-long lesions.

Electronic Blood Vessel

Summary Advances in bioelectronics have great potential to address unsolved biomedical problems in the cardiovascular system. By using poly(L-lactide-co-ϵ-caprolactone), which encapsulates liquid metal to make flexible and biodegradable electrical circuitry, we develop an electronic blood vessel that can integrate flexible electronics with three layers of blood-vessel cells, to mimic and go beyond the natural blood vessel. It can improve the endothelialization process through electrical stimulation and can enable controlled gene delivery into specific parts of the blood vessel via electroporation. The electronic blood vessel has excellent biocompatibility in the vascular system and shows great patency 3 months post-implantation in a rabbit model. The electronic blood vessel would be an ideal platform to enable diagnostics and treatments in the cardiovascular system and can greatly empower personalized medicine by creating a direct link of the vascular tissue-machine interface.

Hypotensive Response on Cardiopulmonary Stress Test Predicts Elevated Pulmonary Capillary Wedge Pressure and Reduced Cardiac Output in Patients Undergoing Evaluation for Left Ventricular Assist Device

Purpose Cardiopulmonary stress test (CPX) and right heart catheterization (RHC) are integral part of the routine evaluation for ventricular assist device (LVAD) therapy. A hypotensive response, or failure to augment systolic blood pressure at peak stress above resting values might be a marker of high-risk physiology. We sought to evaluate the association between hypotensive response on CPX and invasive hemodynamics in patients undergoing LVAD evaluation. Methods This was a retrospective single center study of consecutive adult patients who underwent LVAD surgery at our center between 1/2011 and 1/2019. Only patients with both CPX and RHC performed within 12 months of implantation were included. Hypotensive response was defined as a peak exercise systolic blood pressure lower than the resting systolic blood pressure. Central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP) and cardiac index determined using the thermodilution method (CI) were collected from RHC data. Multivariable Cox regression analysis was performed to evaluate the association between CPX data and hemodynamics. Results A total of 313 patients were included in the study and 115 met inclusion criteria. The mean age was 60.1 years, 66% were designated bridge to transplant (BTT) and the majority (85%) were classified as INTERMACS 3-5. Forty seven percent (54/115) developed a hypotensive response during testing. The group had a mean PCWP of 23.7 mmHg and a mean CI of 1.7 L/min/m2. In contrast, patients with normal blood pressure response had a significantly lower PCWP (19.8 mmHg; P=0.011) and significantly higher CI (2.0 L/min/m2; p=0.030). There was no difference in CVP values between the groups. Mean exercise duration was 6 minutes and 1 seconds in the hypotensive group, and 7 minutes 8 seconds in the group with normal blood pressure response. Conclusion A hypotensive response on CPX performed prior to LVAD implantation is associated with more severely abnormal hemodynamics. Identification of this high risk feature earlier has the potential to improve outcomes by preventing late LVAD implantation.

Assessing the Sustainability and Acceptance Rate of Cost-Effective Household Water Treatment Systems in Rural Communities of Makwane Village, South Africa

The current study investigated the acceptance rate and long-term effectiveness of cost-effective household water treatment systems deployed in Makwane Village. A structured questionnaire was used prior to implementation to collect information such as level of education, level of employment, and knowledge about point-of-use water treatment systems in the target area. The long-term effectiveness was determined by factors such as the Escherichia coli removal efficiency, turbidity reduction, silver leached, and flow rate of the household water treatment devices. The results of the survey prior to deployment revealed that only 4.3% of the community had a tertiary qualification. Moreover, 54.3% of the community were unemployed. The results further revealed that 65.9% of the community were knowledgeable about other point-of-use water treatment methods. The acceptance rate, which was found to be initially higher (100%), reduced after three months of implantation (biosand filter with zeolite-silver clay granular—82.9%; silver-impregnated porous pot filters—97.1%). Moreover, the long-term effectiveness was determined, taking into consideration the adoption rate, and it was found that silver-impregnated porous pot filters have a long life compared to biosand filter with zeolite-silver clay granular. Although household water treatment systems can effectively reduce the burden of waterborne diseases in impoverished communities, the success of adoption is dependent on the targeted group. This study highlights the significance of involving community members when making the decision to scale up household water treatment devices in rural areas for successful adoption.

A 3D construct based on mesenchymal stromal cells, collagen microspheres and plasma clot supports the survival, proliferation and differentiation of hematopoietic cells in vivo.

The hematopoietic niche is a specialized microenvironment that supports the survival, proliferation and differentiation of hematopoietic stem progenitor cells (HSPCs). Three-dimensional (3D) models mimicking hematopoiesis might allow in vitro and in vivo studies of the hematopoietic (HP) process. Here, we investigate the capacity of a 3D construct based on non-adherent murine bone marrow mononuclear cells (NA-BMMNCs), mesenchymal stromal cells (MSCs) and collagen microspheres (CMs), all embedded into plasma clot (PC) to support in vitro and in vivo hematopoiesis. Confocal analysis of the 3D hematopoietic construct (3D-HPC), cultured for 24h, showed MSC lining the CM and the NA-BMMNCs closely associated with MSC. In vivo hematopoiesis was examined in 3D-HPC subcutaneously implanted in mice and harvested at different intervals. Hematopoiesis in the 3D-HPC was evaluated by histology, cell morphology, flow cytometry, confocal microscopy and hematopoietic colony formation assay. 3D-HPC implants were integrated and vascularized in the host tissue, after 3months of implantation. Histological studies showed the presence of hematopoietic tissue with the presence of mature blood cells. Cells from 3D-HPC showed viability greater than 90%, expressed HSPCs markers, and formed hematopoietic colonies, in vitro. Confocal microscopy studies showed that MSCs adhered to the CM and NA-BMMNCs were scattered across the 3D-HPC area and in close association with MSC. In conclusion, the 3D-HPC mimics a hematopoietic niche supporting the survival, proliferation and differentiation of HSPCs, in vivo. 3D-HPC may allow evaluation of regulatory mechanisms involved in hematopoiesis.

Tofu as excellent scaffolds for potential bone regeneration

Biomimetic scaffolds present the promising potential for bone regeneration. As a natural gel-like traditional food, tofu with porous architecture and proved biological safety indicated a good potential to be a natural scaffold and easy to be improved by surface modification. Hereon, we fabricated the tofu-based scaffolds and systematically explored the potential for bone tissue engineering. In addition, the collagen has been introduced by simple coating to further enhance the surface compatibility of the tofu-based scaffold in bone regeneration. The results showed that the tofu-based scaffolds possessed good porous structure and cytocompatibility. Notably, the tofu-based scaffolds could improve the expression of osteogenesis-related genes and proteins, leading to better bone regeneration after 2 months of implantation. All the results indicated that tofu would become an outstanding sustainable natural porous scaffold for bone regeneration with excellent bioactivities.

Evaluation of Bilayer Silk Fibroin Grafts for Tubular Esophagoplasty in a Porcine Defect Model.

Surgical reconstruction of tubular esophageal defects with autologous gastrointestinal segments is the gold standard treatment to replace damaged or diseased esophageal tissues. Unfortunately, this approach is associated with adverse complications, including dysphagia, donor-site morbidity, and in some cases patient death. Bilayer silk fibroin (BLSF) scaffolds were investigated as alternative, acellular grafts for tubular esophagoplasty in a porcine defect model for 3 months of implantation. Adult Yucatan mini-swine (n = 5) were subjected to esophageal reconstruction with tubular BLSF grafts (2 cm in length) in combination with transient esophageal stenting for 2 months followed by a 1-month period, where the graft site was unstented. All animals receiving BLSF grafts survived and were capable of solid food consumption, however strictures were noted at graft regions in 60% of the experimental cohort between 2 and 3 months postop and required balloon dilation. In addition, fluoroscopic analysis showed peristaltic function in only 1/5 neotissues. Following swine harvest at 3 months, ex vivo tissue bath evaluations revealed that neoconduits exhibited contractile responses to carbachol, electric field stimulation, and KCl, whereas sodium nitroprusside and isoproterenol induced relaxation effects. Histological (Masson's Trichrome) and immunohistochemical analyses of regenerated tissue conduits showed a stratified, squamous epithelium expressing pan-cytokeratins buttressed by a vascularized lamina propria containing a smooth muscle-rich muscularis mucosa surrounded by a muscularis externa. Neuronal density, characterized by the presence of synaptophysin-positive boutons, was significantly lower in neotissues in comparison to nonsurgical controls. BLSF scaffolds represent a promising platform for the repair of tubular esophageal defects, however improvements in scaffold design are needed to reduce the rate of complications and improve the extent of constructive tissue remodeling. Impact statement The search for a superior "off-the-shelf" scaffold capable of repairing tubularesophageal defects as well as overcoming limitations associated with conventional autologous gastrointestinal segments remains elusive. The purpose of this study was to investigate the performance of an acellular, bilayer silk fibroin graft (BLSF) for tubular esophagoplasty in a porcine model. Our results demonstrated that BLSF scaffolds supported the formation of tubular neotissues with innervated, vascularized epithelial and muscular components capable of contractile and relaxation responses. BLSF scaffolds represent a promising platform for esophageal tissue engineering.

Role of Platelet-Rich Plasma in Spinal Fusion Surgery: Systematic Review and Meta-Analysis.

Background Platelet-rich plasma (PRP) has been used very successfully in enhancing bone fusion in animal experiments. Also, the efficaciousness of PRP in other specialties of medicine such as dentistry, dermatology ophthalmology, and sports medicine is well documented. But the use of PRP to augment bone fusion after spinal surgery in humans is still controversial. We conducted a meta-analysis to determine the role of PRP in enhancing spinal fusion by fastening the rate of new bone formation and decreasing pain after spinal surgery in humans. Methods We searched PubMed, EMBASE, and the Cochrane Library studies that compared PRP versus control in enhancing spinal fusion after deformity correction. Results Five retrospective studies with 253 participants and nine prospective cohort studies with 460 participants were identified. The bone fusion rate was excellent for studies that used a high platelet concentration in PRP relative to control (odds ratio (OR) = 4.35, 95% confidence interval (CI) (2.13, 8.83), and P < 0.05) while bone fusion was poor to studies that used a low concentrate of platelet in PRP relative to control. The rate of new bone formation was high in the PRP group compared to the control group with the mean difference in Hounsfield unit (HU) 144.91 (95% CI (80.63, 209.18), P < 0.05). Time to bone fusion was short in the PRP group during the first six months of surgery relative to the control group with a mean difference of −2.03 (95% CI (−2.35, −1.7); P < 0.05). No difference was found in pain reduction by visual analog score (VAS) between the PRP group and control. Conclusion PRP facilitates new bone formation and bone fusion with a minimum concentration of the growth factor 5 times that of the peripheral blood. PRP stimulatory effects are not continuous and are very effective within six months of implantation.

Noninvasive Tracking of Hematopoietic Stem Cells in a Bone Marrow Transplant Model.

The hematopoietic stem cell engraftment depends on adequate cell numbers, their homing, and the subsequent short and long-term engraftment of these cells in the niche. We performed a systematic review of the methods employed to track hematopoietic reconstitution using molecular imaging. We searched articles indexed, published prior to January 2020, in PubMed, Cochrane, and Scopus with the following keyword sequences: (Hematopoietic Stem Cell OR Hematopoietic Progenitor Cell) AND (Tracking OR Homing) AND (Transplantation). Of 2191 articles identified, only 21 articles were included in this review, after screening and eligibility assessment. The cell source was in the majority of bone marrow from mice (43%), followed by the umbilical cord from humans (33%). The labeling agent had the follow distribution between the selected studies: 14% nanoparticle, 29% radioisotope, 19% fluorophore, 19% luciferase, and 19% animal transgenic. The type of graft used in the studies was 57% allogeneic, 38% xenogeneic, and 5% autologous, being the HSC receptor: 57% mice, 9% rat, 19% fish, 5% for dog, porcine and salamander. The imaging technique used in the HSC tracking had the following distribution between studies: Positron emission tomography/single-photon emission computed tomography 29%, bioluminescence 33%, fluorescence 19%, magnetic resonance imaging 14%, and near-infrared fluorescence imaging 5%. The efficiency of the graft was evaluated in 61% of the selected studies, and before one month of implantation, the cell renewal was very low (less than 20%), but after three months, the efficiency was more than 50%, mainly in the allogeneic graft. In conclusion, our review showed an increase in using noninvasive imaging techniques in HSC tracking using the bone marrow transplant model. However, successful transplantation depends on the formation of engraftment, and the functionality of cells after the graft, aspects that are poorly explored and that have high relevance for clinical analysis.