[Show abstract][Hide abstract] ABSTRACT: Human acellular dermal matrix is used for ventral hernia repair, as it resists infection and remodels by means of surrounding tissue. However, the tissue source and impact of basement membrane on cell and vessel infiltration have not been determined. The authors hypothesized that musculofascia would be the primary tissue source of cells and vessels infiltrating into human acellular dermal matrix and that the basement membrane would inhibit infiltration.
Fifty-six guinea pigs underwent inlay human acellular dermal matrix ventral hernia repair with the basement membrane oriented toward or away from the peritoneum. At postoperative weeks 1, 2, or 4, repair sites were completely excised. Histologic and immunohistochemical analyses were performed to quantify cell and vessel density within repair-site zones, including interface (lateral, beneath musculofascia) and center (beneath subcutaneous fat) zones. Cell and vessel quantities were compared as functions of zone, basement membrane orientation, and time.
Cellular and vascular infiltration increased over time universally. The interface demonstrated greater mean cell density than the center (weeks 1 and 2, p = 0.01 and p < 0.0001, respectively). Cell density was greater with the basement membrane oriented toward the peritoneum at week 4 (p = 0.02). The interface zone had greater mean vessel density than the center zone at week 4 (p < 0.0001). Orienting the basement membrane toward the peritoneum increased vessel density at week 4 (p = 0.0004).
Cellular and vascular infiltration into human acellular dermal matrix for ventral hernia repairs was greater from musculofascia than from subcutaneous fat, and the basement membrane inhibited cellular and vascular infiltration. Human acellular dermal matrix should be placed adjacent to the best vascularizing tissue to improve fibrovascular incorporation.
Plastic and Reconstructive Surgery 04/2012; 129(4):888-96. DOI:10.1097/PRS.0b013e3182450ae5 · 2.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Human acellular dermal matrix (HADM) and non-cross-linked porcine acellular dermal matrix (ncl-PADM) are clinically useful for complex ventral hernia repair. Direct comparisons between the two in vivo are lacking, however. This study compared clinically relevant early outcomes with these bioprosthetic materials when used for ventral hernia repair.
Seventy-two guinea pigs underwent inlay repair of surgically created hernias with HADM (n = 37) or ncl-PADM (n = 35). Repair sites were harvested at 1, 2, or 4 weeks postoperatively. Adhesions were graded and quantified. Mechanical testing and histologic and immunohistologic (factor VIII) analyses of cellular and vascular infiltration were performed.
No infections or recurrent hernias occurred. No difference was observed in mean adhesion surface area or tenacity between groups. Mean cellular infiltration (p < 0.002, weeks 1 and 4; p < 0.006, week 2) and vascular infiltration (p < 0.0003, week 1; p < 0.0001, weeks 2 and 4) were greater in HADM. Ultimate tensile strength at the implant-musculofascia interface increased over time with both materials, but no difference was observed at 4 weeks. The mean ultimate tensile strength of explanted ncl-PADM itself was consistently greater than that of HADM. The elastic modulus (stiffness) did not differ between groups at the interface but was greater in explanted ncl-PADM (p < 0.0001, weeks 1 and 2; p < 0.02, week 4).
Both HADM and ncl-PADM become infiltrated with host cells and blood vessels within 4 weeks and have similar musculofascia-bioprosthetic interface strength. However, HADM has greater cellular and vascular infiltration. Longer-term studies will help determine whether later differences in material strength, stiffness, and remodeling affect hernia and/or bulge incidence.
Plastic and Reconstructive Surgery 06/2011; 127(6):2321-32. DOI:10.1097/PRS.0b013e318213a053 · 2.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Purpose: Complex ventral hernia repair is frequently performed with human acellular dermal matrix (HADM), as it remodels readily. Studies have yet to evaluate the tissue source, timing, and quantity of cellular and vascular infiltration into HADMs for ventral hernia repair. The impact of the biomaterial basement membrane (BM) on cellular and vascular infiltration also remains to be determined. We evaluated the in vivo metrics of fibrovascular remodeling with focus on the relative contribution from adjacent tissue (musculofascia versus fat) and BM effects on cellular and vascular infiltration in HADM.
Methods: An established acute ventral hernia model was used. Fifty-six guinea pigs underwent inlay, bridged ventral hernia repair with HADM (AlloDerm; LifeCell, Branchburg, NJ). HADMs were oriented with the BM toward or away from the peritoneal cavity. At postoperative week 1, 2, or 4, abdominal wall repairs were excised. Repair site adhesions (tenacity and surface area) were quantified. Histologic and immunohistochemical (factor VIII) analyses were performed to quantify cellular and vascular density within repair-site cross-sections, as well as within the interface (dorsal to musculofascial edge) and center (dorsal to subcutaneous fat) mesh zones. Subgroup analyses were performed; the quantity of cellular and vascular infiltration was compared as functions of BM orientation, location within the HADM, and post-implantation time.
Results: HADM infiltration with host cells and vessels increased over time in all groups. There were no differences in adhesion strength or surface area between groups. BM oriented away from the peritoneal cavity reduced vascular infiltration at all timepoints. The greatest magnitude of difference in vascular infiltration occurred in week 4 (68+/-36 versus 129+/-35 vessels/mm2; p = 0.002). In addition, vascular infiltration from the interface zone was greater than that from the center at all timepoints. Cellular infiltration was not significantly affected by BM orientation or adjacent tissue type (cross-section zone) at any timepoint.
Conclusion: HADM undergoes robust cellular and vascular infiltration within 4 weeks. HADM cellularization was not significantly affected by BM orientation or location within the repair site. However, HADM vascularization was delayed by the BM and slower underneath subcutaneous fat. These results suggest that both subcutaneous fat and musculofascia contribute to cellularization and vascularization of bridged HADM repairs, and that orienting the BM toward the peritoneal cavity may be advantageous for fibrovascular remodeling.
[Show abstract][Hide abstract] ABSTRACT: Porcine acellular dermal matrices (PADMs) have been used clinically for abdominal wall repair. The newer non-cross-linked PADMs, however, have not been directly compared with cross-linked PADMs. We hypothesized that chemical cross-linking affects the biologic host response to PADMs used to repair ventral hernias.
Fifty-eight guinea pigs underwent inlay repair of surgically created ventral hernias using cross-linked or non-cross-linked PADM. After animals were sacrificed at 1, 2, or 4 weeks, the tenacity of and surface area involved by adhesions to the repair sites were measured. Sections of the repair sites, including the bioprosthesis-musculofascia interface, underwent histologic analysis of cellular and vascular infiltration plus mechanical testing.
Compared with cross-linked PADM repairs, non-cross-linked PADM repairs had a significantly lower mean tenacity grade of adhesions at all timepoints and mean adhesion surface area at week 1. Mean cellular and vascular densities were significantly higher in non-cross-linked PADM at all timepoints. Cells and vessels readily infiltrated into the center of non-cross-linked PADM, but encapsulated cross-linked PADM, with a paucity of penetration into it. Mechanical properties were similar for the two PADMs (in isolation) at all timepoints; however, at the bioprosthesis-musculofascia interface, both elastic modulus and ultimate tensile strength were significantly higher at weeks 1 and 2 for non-cross-linked PADM.
Non-cross-linked PADM is rapidly infiltrated with host cells and vessels; cross-linked PADM becomes encapsulated. Non-cross-linked PADM causes weaker adhesions to repair sites while increasing the mechanical strength of the bioprosthesis-musculofascia interface at early timepoints. Non-cross-linked PADM may have early clinical advantages over cross-linked PADM for bioprosthetic abdominal wall reconstruction.
Journal of the American College of Surgeons 09/2010; 211(3):368-76. DOI:10.1016/j.jamcollsurg.2010.04.024 · 5.12 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Non-cross-linked porcine acellular dermal matrices have been used clinically for abdominal wall repair; however, their biologic and mechanical properties and propensity to form visceral adhesions have not been studied. The authors hypothesized that their use would result in fewer, weaker visceral adhesions than polypropylene mesh when used to repair ventral hernias and form a strong interface with the surrounding musculofascia.
Thirty-four guinea pigs underwent inlay repair of surgically created ventral hernias using polypropylene mesh, porcine acellular dermal matrix, or a composite of the two. The animals were killed at 4 weeks, and the adhesion tenacity grade and surface area of the repair site involved by adhesions were measured. Sections of the repair sites, including the implant-musculofascia interface, underwent histologic analysis and uniaxial mechanical testing.
The incidence of bowel adhesions to the repair site was significantly lower with the dermal matrix (8 percent, p < 0.01) and the matrix/mesh combination (0 percent, p < 0.001) than with polypropylene mesh alone (70 percent). The repairs made with the matrix or the matrix/mesh combination, compared with the polypropylene mesh repairs, had significantly lower mean adhesion surface areas [12.8 percent (p < 0.001), 9.2 percent (p < 0.001), and 79.9 percent] and grades [0.6 (p < 0.001), 0.6 (p < 0.001), and 2.9]. The dermal matrix underwent robust cellular and vascular infiltration. The ultimate tensile strength at the implant-musculofascia interface was similar in all groups.
Porcine acellular dermal matrix becomes incorporated into the host tissue and causes fewer adhesions to repair sites than does polypropylene mesh, with similar implant-musculofascia interface strength. It also inhibits adhesions to adjacent dermal matrix in the combination repairs. It has distinct advantages over polypropylene mesh for complex abdominal wall repairs, particularly when material placement directly over bowel is unavoidable.
Plastic and Reconstructive Surgery 11/2009; 125(1):167-76. DOI:10.1097/PRS.0b013e3181c2a6ed · 2.99 Impact Factor