An Absorbable Hydrogel Spray Reduces Postoperative Mediastinal Adhesions After Congenital Heart Surgery

Hydrogels in cardiac tissue engineering: application and challenges

Cardiovascular disease remains the leading cause of global mortality. Current stem cell therapy and heart transplant therapy have limited long-term stability in cardiac function. Cardiac tissue engineering may be one of the key methods for regenerating damaged myocardial tissue. As an ideal scaffold material, hydrogel has become a viable tissue engineering therapy for the heart. Hydrogel can not only provide mechanical support for infarcted myocardium but also serve as a carrier for various drugs, bioactive factors, and cells to increase myocardial contractility and improve the cell microenvironment in the infarcted area, thereby improving cardiac function. This paper reviews the applications of hydrogels and biomedical mechanisms in cardiac tissue engineering and discusses the challenge of clinical transformation of hydrogel in cardiac tissue engineering, providing new strategies for treating cardiovascular diseases.

Ultrasound-guided Hydrogel Injection Provides Better Therapeutic Effects After Hand Tendon Surgery Than Intraoperative Injection: A Randomized Controlled Trial

BACKGROUND

Hydrogels are used to provide a barrier against peritendinous adhesion formation, but when implanted intraoperatively, they degrade rapidly and aggravate early inflammatory pain. It is uncertain whether clinical efficacy can be improved by avoiding the inflammatory phase when hydrogels are delivered during adhesion formation.

QUESTIONS/PURPOSES

(1) Compared with intraoperative hydrogel application, does ultrasound-guided postoperative application result in better total active motion (TAM) at 12 months after tendon injury? (2) Does ultrasound-guided postoperative application of hydrogels result in lower pain, better function, and better satisfaction?

METHODS

This open-label, prospective, single-center, randomized controlled trial was conducted by reparative and reconstructive surgeons at the National Orthopedics Clinical Medical Center, Shanghai, People's Republic of China. Between May 2021 and December 2022, 53% (168 of 317) of patients who met our inclusion criteria were recruited, and 47% (149 of 317) of patients were excluded because of the exclusion criteria. Finally, 84 patients were randomized to the postoperative group to receive ultrasound-guided carboxymethyl chitosan (CMC) hydrogel delayed injection, and 84 patients were randomized to the intraoperative group to receive CMC hydrogel intraoperative application. Another 8% (7 of 84) of patients in the postoperative group and 10% (8 of 84) of patients in the intraoperative group were lost before the minimum study follow-up time of 1 year or had incomplete datasets, leaving 91% (153 of 168) of patients with data for analysis. Data on outcome events were analyzed according to the intention-to-treat principle, which included all patients who underwent randomization. Follow-up visits were completed at 3 weeks, 6 weeks, 3 months, 6 months, and 12 months after tendon repair. The primary outcome was TAM (ie, the sum of the degrees of active metacarpophalangeal joint, proximal interphalangeal joint, and distal interphalangeal joint flexion less the degrees from full extension; minimum clinically important difference [MCID] 20°) at 12 months. Secondary outcomes included pain (measured with a VAS; range 0 to 10, a higher score indicating worse pain; MCID 0.6), Michigan Hand Outcomes Questionnaire activities of daily living (MHQ-ADL) score (range 0 to 100, a higher score indicating better outcomes; MCID 10.1), and MHQ satisfaction (MHQ-SAT) score (range 0 to 100, a higher score indicating better outcomes; MCID 33.0).

RESULTS

At 12 months, the ultrasound-guided postoperative injection group had improved TAM (intraoperative 189° [95% CI 179° to 199°] versus postoperative 209° [95% CI 199° to 219°], mean difference 20° [95% CI 6° to 35°]; p = 0.006; the mean difference in the primary outcome fulfilled the MCID value at all time points). At 6 weeks, we found no clinically important difference in VAS pain scores among groups (intraoperative mean ± SD 2.0 ± 1.0 versus postoperative 1.7 ± 1.0, mean difference 0.3 [95% CI 0.1 to 0.7]; p = 0.02); however, at 3 weeks, the VAS pain scores showed clinically important difference among groups (3.6 ± 1.4 versus 2.9 ± 1.2, mean difference 0.7 [95% CI 0.3 to 1.1]; p = 0.001). At 3 months, the ultrasound-guided postoperative injection group had higher MHQ-ADL scores (intraoperative 62 ± 10 versus postoperative 75 ± 10, mean difference 13 [95% CI 11 to 17]; p < 0.001), and the mean difference of MHQ-ADL scores reached the MCID value at all time points. At 3 months, there was no clinically important difference in MHQ-SAT scores between groups (intraoperative 62 ± 8 versus postoperative 70 ± 8, mean difference 8 [95% CI 6 to 11]; p < 0.001).

CONCLUSION

Compared with intraoperative CMC hydrogel injection, postoperative ultrasound-guided injection improved the TAM and function of the affected limb, showed a short-term pain control effect, and did not increase the risk of complications. Clinical trials are needed to confirm the safety and efficacy of ultrasound-guided postoperative injection of CMC hydrogels and to determine the most effective dose and the health and economic benefits of treatment.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Application of Hydrogels in Cardiac Regeneration

Myocardial infarction (MI) is a leading cause of death globally. Due to limited cardiac regeneration, infarcted myocardial tissue is gradually replaced by cardiac fibrosis, causing cardiac dysfunction, arrhythmia, aneurysm, free wall rupture, and sudden cardiac death. Thus, the development of effective methods to promote cardiac regeneration is extremely important for MI treatment. In recent years, hydrogels have shown promise in various methods for cardiac regeneration. Hydrogels can be divided into natural and synthetic types. Different hydrogels have different features and can be cross-linked in various ways. Hydrogels are low in toxicity and highly stable. Since they have good biocompatibility, biodegradability, and transformability, moderate mechanical properties, and proper elasticity, hydrogels are promising biomaterials for promoting cardiac regeneration. They can be used not only as scaffolds for migration of stem cells, but also as ideal carriers for delivery of drugs, genetic materials, stem cells, growth factors, cytokines, and small molecules. In this review, the application of hydrogels in cardiac regeneration during or post-MI is discussed in detail. Hydrogels open a promising new area in cardiac regeneration for treating MI.

Prospects for prevention of adhesion process during cardiac surgical interventions

The article is devoted to the problem of prevention of adhesions in cardiac surgery. It was determined that the problem is urgent due to the increase in the number of heart surgeries. The formation of adhesions is a reaction of the body after surgery, which is a stage of healing and partly performs a protective function. Nevertheless, the presence of adhesions violates the mechanical properties of the heart, negatively affects central hemodynamics, complicates the surgeon’s task during repeated surgical interventions and increases the risk of repeated operations.It has been shown that at present, for the prevention of adhesions, researchers tend to use biodegradable barrier materials with biocompatibility and the ability to dissolve after performing the barrier function. The main anti-adhesion agents used in cardiac surgery are membranes and gels. The requirements for an “ideal” agent for the prevention of adhesion were determined: biocompatibility, no irritating effect, no effect on wound healing, suppression of the growth of connective tissue in the pericardium.Conclusions. Until now, none of the funds has all the necessary qualities to prevent adhesion in the pericardium. Therefore, the search for effective methods for the prevention of postoperative adhesions remains relevant for cardiac surgery.

4-Arm PEG-Functionalized Decellularized Pericardium for Effective Prevention of Postoperative Adhesion in Cardiac Surgery

Postoperative adhesions are a very common and serious complication in cardiac surgery, and the development of an effective anti-adhesion membrane showing resistance to the physical stimulus generated by the pulsation of the heart is desirable. In this study, an anti-adhesion material was developed through amine coupling between decellularized bovine pericardia (dBPCs) and 4-arm poly(ethylene glycol) succinimidyl glutarate (4-arm PEG-NHS) for the postoperative care of cardiac surgical patients. The efficacy of the 4-arm PEG-functionalized dBPCs in the prevention of adhesions after cardiac surgery was investigated in a rabbit heart adhesion model. The dBPCs meet the requirements for biocompatibility, flexibility, and sufficient suturable strength, and the 4-arm PEG moieties provide an anti-adhesion effect by the high excluded volume interactions of the PEG chains with proteins. The 4-arm PEG-functionalized dBPCs had a significantly greater anti-adhesion effect than the other materials tested and showed re-establishment of the mesothelial monolayer. These results suggested that the 4-arm PEG-functionalized dBPCs are a favorable material for an anti-adhesion membrane.

"BAX602" in Preventing Surgical Adhesion after Extracorporeal Ventricular Assist Device Implantation for Refractory Congestive Heart Failure: Study Protocol for a Multicenter Randomized Clinical Trial

BACKGROUND

The high surgical risk in redo cardiac surgery is largely attributed to adhesions around the epicardium and the great vessels. BAX602 is an adhesion prevention reagent composed of two synthetic polyethylene glycols. Spraying BAX602 over the epicardium and the great vessels reportedly contributes to adhesion prevention after pediatric cardiac surgery. The present study aims to evaluate the safety and effectiveness of BAX602 spray in patients undergoing extracorporeal ventricular assist device implantation surgery to treat refractory congestive heart failure.

METHODS AND DESIGN

This investigator-initiated, multicenter, pivotal, two-arm, open-label, randomized trial will include a total of 30 patients. The primary outcome measure is the severity of adhesions, which will be evaluated during re-sternotomy surgery performed 2-12 weeks after the primary extracorporeal ventricular assist device implantation surgery. The adhesion severity will be evaluated at five predefined sites using a four-grade adhesion evaluation score (0 = no adhesion; 1 = filmy and avascular adhesion; 2 = dense/vascular adhesion; 3 = cohesive adhesion). This measure will be summarized in two ways to evaluate the effect of BAX602: (1) the total score of the severity of adhesions at all five sites (ranging from 0 to 15), and (2) the total number of sites with dense/vascular or cohesive adhesions (ranging from 0 to 5).

ETHICS AND DISSEMINATION

The study findings will be disseminated at regional, national, and international conferences and through peer-reviewed scientific journals.

TRIAL REGISTRATION

The trial was registered in the UMIN Clinical Trials Registry (UMIN-CTR: UMIN000038998) on 6 January 2020.