3D Printed Anchoring Sutures for Permanent Shaping of Tissues

Characterization of a Decellularized Sheep Pulmonary Heart Valves and Analysis of Their Capability as a Xenograft Initial Matrix Material in Heart Valve Tissue Engineering

In order to overcome the disadvantages of existing treatments in heart valve tissue engineering, decellularization studies are carried out. The main purpose of decellularization is to eliminate the immunogenicity of biologically derived grafts and to obtain a scaffold that allows recellularization while preserving the natural tissue architecture. SD and SDS are detergent derivatives frequently used in decellularization studies. The aim of our study is to decellularize the pulmonary heart valves of young Merino sheep by using low-density SDS and SD detergents together, and then to perform their detailed characterization to determine whether they are suitable for clinical studies. Pulmonary heart valves of 4-6-month-old sheep were decellularized in detergent solution for 24 h. The amount of residual DNA was measured to determine the efficiency of decellularization. Then, the effect of decellularization on the ECM by histological staining was examined. In addition, the samples were visualized by SEM to determine the surface morphologies of the scaffolds. A uniaxial tensile test was performed to examine the effect of decellularization on biomechanical properties. In vitro stability of scaffolds decellularized by collagenase treatment was determined. In addition, the cytotoxic effect of scaffolds on 3T3 cells was examined by MTT assay. The results showed DNA removal of 94% and 98% from the decellularized leaflet and pulmonary wall portions after decellularization relative to the control group. No cell nuclei were found in histological staining and it was observed that the three-layer leaflet structure was preserved. As a result of the tensile test, it was determined that there was no statistically significant difference between the control and decellularized groups in the UTS and elasticity modulus, and the biomechanical properties did not change. It was also observed that decellularized sheep pulmonary heart valves had no cytotoxic effect. In conclusion, we suggest that the pulmonary valves of decellularized young Merino sheep can be used as an initial matrix in heart valve tissue engineering studies.

Barbed Sutures for Total Hip and Knee Arthroplasty Have Shorter Wound Closure Time and are Cost-Effective in Comparison to Traditional Sutures: A Systematic Review and Meta-analysis of 16 Randomized Controlled Trials

PURPOSE

Surgical wound closure is of paramount importance, especially in total joint replacement surgeries wherein correct closure technique not only aids in rapid healing, but with lesser complications, we would be looking at a quicker rehabilitation of the patients. Bidirectional barbed sutures appear to reduce the wound closure time in all the planes and are cost-effective in comparison with traditional sutures. This study is aimed at evaluating the efficacy and superiority of bidirectional barbed sutures in comparison to traditional suturing techniques.

METHODS

Electronic databases like Embase, PubMed, Cochrane Library, Lilacs were searched up to February 2021. 16 high-quality randomized-controlled trials (RCT) were selected in this study. The search method identified 2168 total knee replacements (TKR) and 229 total hip replacements (THR) among 2397 patients. All the studies compared barbed sutures with traditional wound closure techniques. Data of wound closure time, overall cost, length of hospital stay, overall wound complications, suture-related complications, range of motion data, and knee society scores were collected and further analyzed.

RESULTS

The baseline patient characteristics were identical among all the included studies. Compared to traditional sutures a significantly decreased wound closure time in both THR and TKRs (p < 0.00001) and cost (p < 0.00001) was noted, although no statistically significant difference was found in overall complications in THRs (p = 0.95) and TKRs (p = 0.69). ROM (p = 0.54-6 weeks after surgery and p = 0.68-3 months after surgery) and Knee society scores (p = 0.92) in both the groups of patients undergoing TKR. However, the length of hospital stay was prolonged in the barbed suture group (p = 0.01), pinpricks (p = 0.02), and broken sutures (p = 0.02).

CONCLUSIONS

Novel methods of wound closure such as barbed sutures achieve satisfactory surgical implementation being more efficient in the form of decreasing the overall wound closure time, with comparable wound complication rates and being cost-effective. But the drawbacks like the incidence of broken sutures and pinpricks are more. Overall using barbed sutures in place of traditional sutures may be considered safe and a viable alternative choice for suturing in total joint replacements.

LEVEL OF EVIDENCE

Level I, Systematic review and Meta-analysis of RCT.

Bio-inspired wettability patterns for biomedical applications

Benefiting from the remarkable wettability heterogeneity, bio-inspired wettability patterns present a progressive and versatile platform for manipulating and patterning liquids, which provides an emerging strategy for operating liquid samples with crucial values in biomedical applications. In this review, we present a general summary of bio-inspired wettability patterns. After a compendious introduction of natural wettability phenomena and their underlying mechanisms, we summarize the general design principles and fabrication methods for preparing artificial wettability materials. Next, we shift to patterned surface wettability with an emphasis on the fabrication approaches. Then, we discuss in detail the various practical applications of wettability patterns in the biomedical field, including cell culture, drug screening and biosensors. Critical thinking about the current challenges and future outlook is also provided. We believe that this review would propel the prosperous development of bio-inspired wettability patterns to flourish in the field of biomedical engineering.

Influence of the integrity of tendinous membrane and fascicle on biomechanical characteristics of tendon-derived scaffolds

The biomechanical characteristics of tendon grafts is essential for tendon reconstructive surgery due to its great role in providing a good mechanical environment for tendon healing and regeneration. In our previous studies, the decellularized tendon slices (DTSs) and decellularized bovine tendon sheets (DBTSs) scaffolds were successfully developed. However, the influence of the integrity of tendinous membrane (endotenon and epitenon) and fascicle on biomechanical characteristics of these two scaffolds was not investigated. In this study, we assessed the integrity of tendinous membrane and fascicle of the tendon derived scaffolds and its effect on the biomechanical characteristics. The results of histological staining indicated that the DBTSs had complete endotenon and epitenon, while DTSs had no epitenon at all, only part of endotenon was remained. Furthermore, the DBTSs, and DTSs with thickness of 900 μm had complete fascicles, while DTSs with thickness less than 600 μm had almost no complete fascicles. The fibrous configuration of epitenon was well-preserved in the surface of the DBTSs but the surface ultrastructure of the DTSs was aligned collagen fibers based on scanning electron microscopy examination. The results of transmission electron microscopy showed that there was no significant difference between the DBTSs and DTSs. Mechanically, the DBTSs and DTSs with thickness of 900 μm showed similar ultimate tensile strength and stiffness to native tendon segments (NTSs). The strain at break and suture retention strength of the DBTSs showed much higher than that of the DTSs (p < 0.05). Additionally, the DBTSs showed higher ultimate load than the DTSs when these scaffolds were sutured with NTSs (p < 0.05) through the modified Kessler technique based on a uniaxial tensile test. This study demonstrated that DTSs may be used as a patch for reinforcing tendon repair, while DBTSs may be used as a bridge for reconstructing tendon defects.

A Tumor-on-a-Chip System with Bioprinted Blood and Lymphatic Vessel Pair

Current in vitro anti-tumor drug screening strategies are insufficiently portrayed lacking true perfusion and draining microcirculation systems, which may post significant limitation in reproducing the transport kinetics of cancer therapeutics explicitly. Herein, we report the fabrication of an improved tumor model consisting of bioprinted hollow blood vessel and lymphatic vessel pair, hosted in a three-dimensional (3D) tumor microenvironment-mimetic hydrogel matrix, termed as the tumor-on-a-chip with bioprinted blood and lymphatic vessel pair (TOC-BBL). The bioprinted blood vessel was perfusable channel with opening on both ends while the bioprinted lymphatic vessel was blinded on one end, both of which were embedded in a hydrogel tumor mass, with vessel permeability individually tunable through optimization of the composition of the bioinks. We demonstrated that systems with different combinations of these bioprinted blood/lymphatic vessels exhibited varying levels of diffusion profiles for biomolecules and anti-cancer drugs. Our TOC-BBL platform mimicking the natural pathway of drug-tumor interactions would have the drug introduced through the perfusable blood vessel, cross the vascular wall into the tumor tissue via diffusion, and eventually drained into the lymphatic vessel along with the carrier flow. Our results suggested that this unique in vitro tumor model containing the bioprinted blood/lymphatic vessel pair may have the capacity of simulating the complex transport mechanisms of certain pharmaceutical compounds inside the tumor microenvironment, potentially providing improved accuracy in future cancer drug screening.