Examination of the early wound healing process under different wound dressing conditions

Recent advancements in natural polymers-based self-healing nano-materials for wound dressing

The field of wound healing has witnessed remarkable progress in recent years, driven by the pursuit of advanced wound dressings. Traditional dressing materials have limitations like poor biocompatibility, nonbiodegradability, inadequate moisture management, poor breathability, lack of inherent therapeutic properties, and environmental impacts. There is a compelling demand for innovative solutions to transcend the constraints of conventional dressing materials for optimal wound care. In this extensive review, the therapeutic potential of natural polymers as the foundation for the development of self-healing nano-materials, specifically for wound dressing applications, has been elucidated. Natural polymers offer a multitude of advantages, possessing exceptional biocompatibility, biodegradability, and bioactivity. The intricate engineering strategies employed to fabricate these polymers into nanostructures, thereby imparting enhanced mechanical robustness, flexibility, critical for efficacious wound management has been expounded. By harnessing the inherent properties of natural polymers, including chitosan, alginate, collagen, hyaluronic acid, and so on, and integrating the concept of self-healing materials, a comprehensive overview of the cutting-edge research in this emerging field is presented in the review. Furthermore, the inherent self-healing attributes of these materials, wherein they exhibit innate capabilities to autonomously rectify any damage or disruption upon exposure to moisture or body fluids, reducing frequent dressing replacements have also been explored. This review consolidates the existing knowledge landscape, accentuating the benefits and challenges associated with these pioneering materials while concurrently paving the way for future investigations and translational applications in the realm of wound healing.

Evaluation of Eruption of Permanent Teeth in Beagle Dog Extraction Sites Filled with Carbonate Apatite

Autologous bone grafting is the primary method for treating alveolar clefts. However, bone grafting materials are desired as alternatives to autogenous bone to reduce surgical invasiveness. Here, we present an animal study evaluating the effect of carbonate apatite (CA) on the spontaneous eruption of permanent teeth. The bone grafting materials included CA, natural bovine bone (BB), and hydroxyapatite (HA). In 15 8-week-old male beagle dogs, the left mandibular deciduous premolars (DP) two and three were extracted and subsequently filled with CA, BB, and HA. The animals were euthanized after a predetermined number of days, and samples were collected for microcomputed tomography and histological evaluation. Spontaneous eruption of the succeeding permanent teeth (P3 and P4) was observed in the CA group at 14 weeks. Delayed eruption of the succeeding permanent teeth was observed in the BB and HA groups. CA could serve as a viable alternative to autogenous bone for treating alveolar clefts.

Development of new bioabsorbable implants with de novo adipogenesis

Poly-L-lactic acid (PLLA) mesh implants containing collagen sponge (CS) were replaced with autologous adipose tissue regeneration in vivo. Herein, we investigated the optimal external frames and internal fillings using poly (lactic-co-ε-caprolactone) (P (LA/CL)), PLLA, and low-molecular-weight PLLA (LMW-PLLA) as the external frame and polyglycolic acid (PGA) nanosheets and CS as the internal filling. We prepared six implants: P (LA/CL) with PGA nano, PLLA with PGA nano, PLLA with CS, PLLA with 1/2 CS, PLLA with 1/4 CS, and LMW-PLLA with CS, and evaluated adipogenesis at 6 and 12 months using a rat inguinal model. The internal spaces in the P (LA/CL) and LMW-PLLA implants collapsed at 6 months, whereas those in the other four implants collapsed at 12 months. Adipose tissue regeneration was not significantly different between the PLLA-implanted groups at 6 and 12 months and was greater than that in the P (LA/CL) with PGA nano and LMW-PLLA with CS groups. The PGA nanosheet inside PLLA was comparable to the CS inside PLLA in the regeneration of adipose tissue and macrophage infiltration. In summary, PLLA is a promising external frame material in which the internal space can be replaced with adipose tissue. Thus, PGA nanosheets are an alternative internal filling material for adipose tissue regeneration.

Current Biomaterials for Wound Healing

Wound healing is the body's process of injury recovery. Skin healing is divided into four distinct overlapping phases: hemostasis, inflammation, proliferation, and remodeling. Cell-to-cell interactions mediated by both cytokines and chemokines are imperative for the transition between these phases. Patients can face difficulties in the healing process due to the wound being too large, decreased vascularization, infection, or additional burdens of a systemic illness. The field of tissue engineering has been investigating biomaterials as an alternative for skin regeneration. Biomaterials used for wound healing may be natural, synthetic, or a combination of both. Once a specific biomaterial is selected, it acts as a scaffold for skin regeneration. When the scaffold is applied to a wound, it allows for the upregulation of distinct molecular signaling pathways important for skin repair. Although tissue engineering has made great progress, more research is needed in order to support the use of biomaterials for wound healing for clinical translation.

Secondary healing property using Neoveil®, a polyglycolic acid bioabsorbable sheet on the oral mucosal defects

Neoveil® is a wound surface-covering agent composed of polyglycolic acid(PGA) effective for secondary healing. This study evaluated the secondary healing property of oral cavity mucosal defects using the PGA sheet. Thirty-four patients who underwent surgical excision of oral benign and malignant lesions, precancerous lesions, and tumors were evaluated. The PGA sheet was placed over the open wound to aid secondary healing. The defects were reviewed post-operatively for secondary healing, contracture, and secondary deformity. Male to female ratio was 20:14, and the mean age was 63.5 years. In all cases, the oral mucosal defect was present after the wide excision of the mucosal lesion. The PGA sheet was used as a surface covering agent which was found to be effective in secondary healing of the wound. Any side effects and adverse reactions which were caused by the PGA sheet was not evident. It can be used to avoid skin graft or free flap reconstruction or deformity from the direct closure in moderate size oral mucosal defect.

Evaluation of the Effects of Covering With Polyglycolic Acid Sheet on Wound Healing: A Pilot Histopathological Study

Purpose: Although the usefulness of polyglycolic acid (PGA) sheet for wound dressing has been recently reported, its histopathological effect on wound healing is not completely elucidated. This pilot study focused on the neo-epithelium formation and the remaining inflammation.

Methods: Full-thickness defects of 8 mm were created on the back of seven-week-old rats. Four rats were divided into the control (raw surface) group and the PGA group, in which the wounds were covered with a PGA sheet. The wounds were assessed on days seven and 12 after wound creation. The length of neo-epithelium on day seven was measured by referring to Masson’s trichrome (MT) and α-smooth muscle actin (α-SMA) staining. The remaining inflammation on days seven and 12 was assessed with ionized calcium-binding adapter molecule 1 (Iba-1) staining.

Results: The average values of neo-epithelium length on day seven measured by referring to the borderline between MT staining and α-SMA expression were 959.2 μm in the control group and 582.2 μm in the PGA group. The number of Iba-1-positive cells on day 12 was significantly higher in the PGA group than in the control group.

Conclusions: To assess the neo-epithelium length and the remaining inflammation, the α-SMA, MT, and Iba-1 staining may be appropriate.

Bioactive anti-inflammatory antibacterial metformin-contained hydrogel dressing accelerating wound healing

Highly efficient wound healing and skin regeneration remain a challenge. Long-term inflammation and bacterial infection can inhibit the healing process and lead to the scar formation. Here, we report a hydrogel (FEM) formed by self-assembly of ε-poly-l-lysine-F127-ε-poly-l-lysine (EPL-F127-EPL) and metformin for wound repair. Especially, the role of metformin-based antibacterial hydrogel in wound healing and repair was investigated for the first time. FEM has inherent multifunctional properties, including controlled metformin release, anti-inflammatory and antibacterial activity, temperature responsiveness, injectable and self-healing capabilities. The in vivo results showed that FEM dressings accelerated the wound healing by stimulating the angiogenesis process of the wound tissue and anti-inflammation. This study shows that the multifunctional metformin-contained hydrogel scaffolds could enhance the wound repair through the anti-inflammation and accelerated angiogenesis, which could also expand the biomedical applications of metformin-based biomaterials.

Is it the Surgeon? A Re-examination of Mid-urethral Sling Complications

OBJECTIVE

To identify potential technical factors during initial mid-urethral sling (MUS) placement that contribute to subsequent sling revision procedures.

METHODS

A retrospective chart review was performed examining synthetic MUS reoperations at a single institution from 2008-2020. The implanting surgeon's operative note, when available, was critically reviewed with respect to trocar placement, sling location, and tensioning technique. The reoperative report was reviewed for aberrant intraoperative findings relating to the index surgery.

RESULTS

A total of 306 women underwent revision of their MUS. Operative reports from the implanting surgeon were available for 276 (90.2%) women. Review of index operative reports revealed 47 unambiguous descriptions of improper technique, including 19 cases of described excessive tensioning and 2 cases of MUS placement despite noted urethral injury during the index case. Indications for reoperation were clinical obstruction (63%), pain (40%), and mesh erosion/exposure (33%). In 186 (67.4%) women, there was an intraoperative finding during the revision that likely contributed to the need for reoperation. Among these 186 women, 110 (59.1%) slings were noted to have been placed too proximally, 78 (41.9%) were over-suspended, and 57 (30.6%) were placed too deep in the periurethral fascia.

CONCLUSION

Review of the index operative note and findings at operative re-exploration of MUS surgeries, often reveals evidence that the initial MUS implantation was technically suboptimal. Such findings suggest that intraoperative surgical technique is a critically important factor contributing to postoperative complications in MUS surgery. This underscores the importance of surgical training and adherence to surgical principles during the placement of a synthetic MUS.

Healing of Open Upper Lip Vermillion Wounds Irradiated with CO2 Laser Immediately After Injury

Objective: To evaluate the healing of open upper lip vermillion wounds irradiated with CO₂ laser immediately after injury.

Background: There are reports of using CO₂ laser therapy on healed wounds for scar tissue reduction. However, limited data exist regarding its use immediately after an injury. Thus, the role of CO₂ laser in wound healing remains unclear.

Methods: Two patients with open upper lip vermillion wounds were treated using CO₂ laser irradiation to the area postsuturing.

Results: Good functional and aesthetic results were obtained from the therapy, with no postoperative pain complaints or infection.

Conclusions: CO₂ laser irradiation, performed immediately after an injury, could be an effective treatment option for open vermillion wounds.

Underwater-adhesive microparticle dressing composed of hydrophobically-modified Alaska pollock gelatin for gastrointestinal tract wound healing

Despite the success of minimally-invasive endoscopic submucosal dissection (ESD) for the treatment of early gastrointestinal cancer, additional symptoms after ESD, including contracture, perforation, bleeding, and esophageal stricture remain. Conventional wound dressings were ineffective in preventing stricture because of poor stability of underwater-adhesives on living tissues. Here, we present a microparticle-based wound dressing with underwater adhesive stability for the treatment of gastrointestinal tract wound healing after ESD. Monodisperse microparticles composed of hydrophobically-modified Alaska pollock gelatin were prepared by self-assembly of gelatin in water-ethanol mixed solvents and thermal crosslinking. Hydrophobic modification of gelatin with aliphatic aldehydes increased adhesion strength to gastric and esophageal submucosal tissues through hydrophobic interaction with living tissues and cohesion force. Optimal hydrophobic modification drastically improved underwater stability of microparticles compared to that of non-modified gelatin and formed a thick, integrated hydrogel layer on tissues. Histological observation of rat skin wound healing models showed that hydrophobically-modified gelatin microparticles decreased the expression levels of α-smooth muscle actin in the dermis layer and could suppress fibrosis and inflammation after ESD. The microparticle wound dressing with high underwater-adhesive stability has enormous therapeutic potential to promote wound healing in the gastrointestinal tract and prevent additional symptoms after ESD. STATEMENT OF SIGNIFICANCE: The goal of this study was to develop wound dressing with strong tissue-adhesive property to living tissues for promoting wound healing after ESD treatment. Monodisperse microparticles composed of hydrophobically-modified Alaska pollock gelatin were prepared by self-assembly of gelatin in water-ethanol mixed solvents and thermal crosslinking. Hydrophobic modification of gelatin with aliphatic aldehydes enhanced adhesion strength to gastric and esophageal submucosal tissues through hydrophobic interaction with living tissues and cohesion force. Optimal hydrophobic modification drastically improved underwater stability of microparticles. The in vivo studies were performed to evaluate the ability of this colloidal wound dressing to suppress fibrosis. This new biomaterial has enormous potential to promote wound healing after ESD.

Dental Rehabilitation for Free Fibula Flap-Reconstructed Mandible with Scar Contracture: A Technical Note

Dental rehabilitation with osseointegrated implants in reconstructed mandibles is a common procedure, but the technique still requires improvement, especially in its reliability and technical simplification. We herein report dental rehabilitation of a free fibula-reconstructed mandible with scar contracture. A vestibuloplasty technique with application of a polyglycolic acid (PGA) sheet is described. The implants were inserted into a viable fibula flap with severe scar contracture of the overlying epithelium resulting from vascular instability in skin paddle. Only the fibula periosteum was sutured after implant insertion; exposed surfaces were covered with a combination of PGA sheet and fibrin sealant. The area with PGA sheet coverage gradually healed with moderate contracture. The epithelium around the almost implants became immobilized. The implant-supported removable partial denture with custom titanium bar was acceptable. Dental rehabilitation is possible for reconstructed mandibles with severe scar contracture. Application of a PGA sheet may be useful for vestibuloplasty in patients with reconstructed mandibles.

Effects of low-level laser therapy on the healing of surgically closed incisions and surgically created open wounds in dogs

OBJECTIVE

To determine the effects of low-level laser therapy (LLLT) on primarily closed incisions and full thickness open wounds in dogs.

STUDY DESIGN

Prospective, masked, placebo-controlled design.

ANIMAL POPULATION

Healthy intact female dogs (n = 10).

METHODS

Dogs underwent bilateral flank ovariectomy procedures, and open wounds were created bilaterally with a punch biopsy. Each side of the dog (incision and open wound) was randomly assigned to the treatment (TX) group or the control (CN) group. The TX group received LLLT once daily for 5 days with a 980-nm laser and a total energy density of 5 J/cm² . The CN group received a sham treatment (laser turned off) for an identical amount of time each day. The wounds were assessed visually; measured; photographed at postoperative days 3, 7, 11, and 14; and biopsied on postoperative days 7 and 14. A 2-way repeated measures multivariate analysis of variance was used to analyze differences between groups.

RESULTS

There was no difference between groups for subjective assessment of healing time and wound measurements (P = .7). There was no difference in histopathologic assessment except that the CN group had more necrosis and perivascular lymphocytes and macrophages at day 7 (P = .03). The TX group had more perivascular lymphocytes and macrophages at day 14 (P = .01).

CONCLUSION

LLLT did not appear to influence the healing of surgically created incisions and small wounds with the methodology reported here.

CLINICAL SIGNIFICANCE

Results of this study do not support recommending LLLT to stimulate healing of uncomplicated, small wounds and incisions.

Role of MicroRNA in Proliferation Phase of Wound Healing

Wound healing is a complex biological process that is generally composed of four phases: hemostasis, inflammation, proliferation, and remodeling. The proliferation phase is crucial for effective healing compared to other phases. Many critical events occur during this phase, i.e., migration of fibroblasts, re-epithelialization, angiogenesis and wound contraction. Chronic wounds are common and are considered a major public health problem. Therefore, there is the increasing need to discover new therapeutic strategies. MicroRNA (miRNA) research in the field of wound healing is in its early phase, but the knowledge of the recent discoveries is essential for developing effective therapies for the treatment of chronic wounds. In this review, we focused on recently discovered miRNAs which are involved in the proliferation phase of wound healing in the past few years and their role in wound healing.