Submucosal injection of micronized acellular dermal matrix: analysis of biocompatibility and durability

Evaluation of Paste-Type Micronized Acellular Dermal Matrix for Soft Tissue Augmentation: Volumetric and Histological Assessment in a Mouse Model

BACKGROUND

A biological injectable material, paste-type micronized acellular dermal matrix (ADM), has been proven effective in wound healing by filling defects through tissue replacement. This study aimed to compare the efficacy of paste-type micronized ADM on soft tissue augmentation with that of the conventional fillers in animal experiments.

METHODS

Two distinct paste-type micronized ADMs, which were mixed with distilled water (mADM) and gelatin (mADM+GEL), respectively, were compared with conventional fillers, hyaluronic acid (HA) and polymethyl methacrylate (COL+PMMA). Thus, four different types of fillers were each injected into the dorsum of nude mice to compare the volume retention and biocompatibility. During the 8-week experimental period, ultrasound and computed tomography (CT) images were obtained for volumetric analysis. Histological evaluation was performed using hematoxylin and eosin and CD 31 staining.

RESULTS

According to the CT images at week 8, the mADM and mADM+GEL showed a higher volume persistence rate of 113.54% and 51.12%, compared with 85.09% and 17.65% for HA and COL+PMMA, respectively. The 2-week interval ultrasound images revealed that the mADM showed a volume increase in width rather than in height, and an increase in height for HA did not vary much. Histological analysis showed marked fibrous invasion and neovascularization with the mADM and mADM+GEL compared to that of the conventional fillers.

CONCLUSIONS

Paste-type micronized ADM showed soft tissue augmentation with similar effectiveness to that of conventional fillers. Therefore, paste-type micronized ADM has potential as an alternative material for a soft tissue filler in tissue replacement.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Application of micronised acellular dermal matrix for primary premature ejaculation: A preliminary study

This study aimed to explore the efficacy of injection of micronised acellular dermal matrix (MADM) particles for treating primary premature ejaculation. This study was a prospective single-arm clinical trial. Thirty patients who met the surgical indications were enrolled. MADM particles, mixed in platelet-rich plasma, were injected into Buck's fascia to spread over the dorsal penile nerve, suppress the influx of nerve impulses and, thus, reduce penis sensitivity. We evaluated the changes according to intravaginal ejaculation latency time using a stopwatch and a premature ejaculation diagnostic tool. Meanwhile, we also recorded sexual partner satisfaction and adverse events. All patients recovered well after surgery with no complications such as infections or allergies. The mean intravaginal ejaculation latency time before surgery was 0.72 ± 0.28 min, compared with 2.41 ± 0.54 min, 2.64 ± 0.41 min, 2.79 ± 0.25 min and 2.89 ± 0.35 min at, respectively, 4, 8, 16 and 20 weeks after surgery. The premature ejaculation diagnostic values and sexual partner satisfaction had significantly improved after treatment. Injection of MADM particles is an effective, safe and simple method for treating premature ejaculation.

Comparison of Volume Retention and Biocompatibility of Acellular Dermal Matrix/Hyaluronic Acid Filler to Autologous Fat Grafts in a Mouse Model

BACKGROUND

Although fat grafting has become a widely used technique in aesthetic and reconstructive surgeries, resorption is still a challenge. Micronized acellular dermal matrix (ADM) has been considered as a stable, biocompatible soft tissue coverage material that can be used as a volume filler. Here, we compared the bioacceptance and sustainability of ADM hyaluronic acid (HA) filler with human fat graft in a mouse model.

METHODS

Harvested human fat and ADM/HA filler were injected randomly on the dorsal side of mice. Thirty-two mice were analyzed over a 7-week period with respect to volume, weight and microscopic evaluations with hematoxylin and eosin (H&E), epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF) staining.

RESULTS

The volume and weight were maintained at 80% and 83%, respectively, in the ADM/HA filler group and 56.5% and 49.7%, respectively, in the fat-grafted group by the 7th week. There were no significant microscopic differences in inflammatory changes and granulation via H&E staining. At 1 and 2 weeks, EGF and VEGF immunostaining intensity scores were lower in the ADM/HA filler group. At 7 weeks, there were no significant differences in immunostaining intensity scores between the two groups.

CONCLUSIONS

During the 7-week experimental period, the ADM/HA filler showed no foreign body reaction and the proper volume was well maintained. This suggests that the ADM/HA filler can possibly be used in small amounts as an alternative to autologous fat grafts.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authorshttp://www.springer.com/00266.

Assessment of outcomes and complications of posterior pharyngeal wall augmentation with dermal fat graft in patients with Velopharyngeal Insufficiency (VPI) after primary cleft palate repair: A pilot study

Introduction

Materials used for posterior pharyngeal wall augmentation have been associated with important complications (exogenous materials) or variable and unpredictable durability (exogenous and endogenous materials); therefore, introducing a different material for augmenting the posterior pharyngeal wall seems necessary for reviving this relatively forgotten technique.

The purpose of this study was to emphasize on the use of a material associated with minimal complications and maximum recovery and durability in correcting VPI and the use of evaluative adjuncts such as nasoendoscopy and videofluoroscopy to assess surgical outcomes.

Methods

In a pilot study, 24 patients underwent posterior pharyngeal wall augmentation with dermal fat graft harvested from the low crease abdominal region. Early and late complications, autologous graft durability in posterior pharynx, and speech improvement were assessed.

Results

There was a significant improvement in hypernasality, nasal emission, and nasal grimace after posterior pharyngeal wall augmentation with dermal fat graft (p<0.0001). The authors observed no significant life-threatening complication. The most evident short-term complication was snoring, which occurred in five patients, and all relieved uneventfully.

Conclusion

The authors believe that augmenting the posterior pharyngeal wall with dermal fat graft is effective in improving hypernasality in patients with moderate velopharyngeal gap size and relatively adequate velar motion. This method has minimal complication profile because of autologous tissue application.

Decellularized materials derived from TSP2-KO mice promote enhanced neovascularization and integration in diabetic wounds

Decellularized biologic scaffolds are gaining popularity over synthetic biomaterials as naturally derived materials capable of promoting improved healing. Nevertheless, the most widely used biologic material - acellular dermal matrix (ADM) - exhibits slow repopulation and remodeling, which prevents integration. Additionally, engineering control of these materials is limited because they require a natural source for their production. In the current report, we demonstrate the feasibility of using genetically engineered animals to create decellularized biologic scaffolds with favorable extracellular matrix (ECM) properties. Specifically, we utilized skin from thrombospondin (TSP)-2 KO mice to derive various decellularized products. Scanning electron microscopy and mechanical testing showed that TSP-2 KO ADM exhibited an altered structure and a reduction in elastic modulus and ultimate tensile strength, respectively. When a powdered form of KO ADM was implanted subcutaneously, it was able to promote enhanced vascularization over WT. Additionally, when implanted subcutaneously, intact slabs of KO ADM were populated by higher number of host cells when compared to WT. In vitro studies confirmed the promigratory properties of KO ADM. Specifically, degradation products released by pepsin digestion of KO ADM induced greater cell migration than WT. Moreover, cell-derived ECM from TSP-2 null fibroblasts was more permissive to fibroblast migration. Finally, ADMs were implanted in a diabetic wound model to examine their ability to accelerate wound healing. KO ADM exhibited enhanced remodeling and vascular maturation, indicative of efficient integration. Overall, we demonstrate that genetic manipulation enables engineered ECM-based materials with increased regenerative potential.

Micronized Cross-Linked Human Acellular Dermal Matrices: An Effective Scaffold for Collagen Synthesis and Promising Material for Tissue Augmentation

Micronized cross-linked human acellular dermal matrices (ADMs) contain the extracellular components necessary for cell integration and tissue remodeling, and have high tensile strength and durability. We hypothesized that such material could serve as a scaffold to enhance the survival of adipocytes in grafted fat. Nude mice (n = 15) were randomly assigned to three groups, each receiving different subcutaneous injections into two dorsal paravertebral areas: fat and saline (control), fat and micronized ADM (E1), and fat and diluted micronized ADM (E2). Digital photographs were taken at 2-week intervals, and the grafted fat volumes and weights were examined after 10 weeks. A histological analysis of the grafted fat was performed, and the expression of vascular endothelial growth factor (VEGF) was examined. The grafted fat volumes decreased over time in all groups; however, at 10 weeks, the grafted fat was better preserved in both experimental groups, with significantly greater weights than in the group C (both, p < 0.001). In the experimental groups, there was more regular arrangement of collagen in the graft tissue, whereas relatively thin, disorderly collagen deposition was observed in the control group. In addition, VEGF expression was significantly greater in the experimental groups than in the control group (p < 0.001). These results are the first to show that micronized cross-linked human ADMs are an excellent scaffold for promoting adipocyte survival and may be an option for maintaining or promoting the in vivo survival of grafted fat.

In Vivo Durability and Safety of Rolled Acellular Dermis in a Submucosal Pocket in Pigs

Objective

This study explored posterior nasopharyngeal augmentation with an acellular dermal matrix sheeting.

Design

Evaluation of the persistence and safety of a submucosal implant of rolled acellular dermis over a 3-month period in a piglet model.

Setting

Institute Hills Facility, part of the Mayo Clinic Rochester health care facility.

Participants

Fifteen 5-week-old domestic piglets of unspecified gender.

Interventions

Twelve piglets were implanted at age 5 weeks with a rolled sheet of acellular dermal matrix (Strattice). Implants were inserted in a submucosal pocket in the soft palate. Three piglets underwent sham operations, with creation of submucosal pockets without implantation. After a 3-month observation period, the palates were harvested for evaluation.

Results

Grossly, persistence of bulk at the surgical site in 5 of the 12 implanted piglets was noted at 3 months. Histologically, no persistence of the dermal matrix could be observed. Incorporation and/or resorption of the dermal matrix occurred with minimal to no host inflammatory response.

Conclusion

This experiment demonstrated the safety of a rolled acellular dermal implant in a submucosal location in a pig model, without surgical complication, host inflammatory reaction, or rejection. Minimal, if any, bulk of the implant persisted in the implanted location after 3 months. Although acellular dermal matrix sheeting appears to be safe and well-tolerated, it does not offer a long-term treatment option for posterior pharyngeal augmentation.

Posterior pharyngeal fat grafting for velopharyngeal insufficiency

Objective : To determine if autologous fat grafting to the posterior pharynx can reduce hypernasality in patients with cleft palate and mild velopharyngeal insufficiency (VPI). Design : Retrospective case series. Setting : Tertiary care center. Patients : Eleven patients with cleft palate status after palatoplasty (with or without secondary speech surgery) with nasendoscopic evidence of VPI. Interventions : Autologous fat was harvested and injected into the posterior pharynx under general anesthesia. Main Outcome Measures : Pre- and postoperative subjective, nasometry, and nasendoscopy data. Apnea-hypopnea indices (AHIs) were also assessed. Comparisons were made using Fisher's exact test, Student's t tests, and relative risk (RR) assessments. Results : An average of 13.1 mL of fat was injected (range: 5 to 22 mL). Mean follow-up was 17.5 months (range: 12 to 25 months). Statistically significant improvements in speech resonance were identified in nasometry (Zoo passage; p  =  .027) and subjective hypernasality assessment (p  =  .035). Eight of the patients (73%) demonstrated normal speech resonance after posterior pharyngeal fat grafting (PPFG) on subjective or objective assessment (p  =  .001). All five patients with previous secondary speech surgeries demonstrated normal speech resonance on similar assessment (RR  =  1.8; p  =  .13). Complete velopharyngeal closure was observed in seven patients on postoperative nasendoscopy. No changes in AHIs were observed (p  =  .581). Conclusion : PPFG may be best used as an adjunct to secondary speech surgery. In this series, PPFG was not accompanied by the negative sequelae of hyponasality, sleep apnea, or airway compromise.

Acellular dermal matrix seeded with adipose-derived stem cells as a subcutaneous implant

BACKGROUND

Soft tissue augmentation using autologous materials usually is associated with high resorption rates. To obtain more durable soft tissue filler, acellular dermal matrix (ADM) was seeded with adipose-derived stem cells (ASCs) in this study.

METHODS

For ADM preparation, split-thickness skin was obtained from the dorsum of two Fischer rats. Harvested skin was acellularized to obtain ADM and subsequently seeded in vitro with ASCs isolated from the same rats. Subcutaneous soft tissue augmentation was carried out in the dorsal area of 20 Fischer rats. The implant materials were ADM (group 1), ADM with ASCs (group 2), collagen type 1 gel (group 3), and collagen type 1 gel with ASCs (group 4). Each specimen was harvested after 8 weeks for quantitative evaluation of thickness, vascular density, and collagen content.

RESULTS

Histologic analysis showed that ASCs were successfully seeded onto ADM. The thickness of the implanted material and the vascular density were highest 8 weeks postoperatively in group 2. The subpanniculus layer became significantly thicker in group 3 than in group 4. The collagen content was significantly higher in group 2 than in the other groups.

CONCLUSION

These findings suggest that ADM seeded with ASCs forms the best implant material in terms of volume maintenance, vascular density, and collagen content.

Fabrication and repair of cartilage defects with a novel acellular cartilage matrix scaffold

The objectives of this study were to develop a three-dimensional acellular cartilage matrix (ACM) and investigate its possibility for use as a scaffold in cartilage tissue engineering. Bovine articular cartilage was decellularized sequentially with trypsin, nuclease solution, hypotonic buffer, and Triton x 100 solution; molded with freeze-drying process; and cross-linked by ultraviolet irradiation. Histological and biochemical analysis showed that the ACM was devoid of cells and still maintained the collagen and glycosaminoglycan components of cartilage. Scanning electronic microscopy and mercury intrusion porosimetry showed that the ACM had a sponge-like structure of high porosity. The ACM scaffold had good biocompatibility with cultured rabbit bone marrow mesenchymal stem cells with no indication of cytotoxicity both in contact and in extraction assays. The cartilage defects repair in rabbit knees with the mesenchymal stem cell-ACM constructs had a significant improvement of histological scores when compared to the control groups at 6 and 12 weeks. In summary, the ACM possessed the characteristics that afford it as a potential scaffold for cartilage tissue engineering.