Biological materials have been developed to avoid the side effects of synthetic implants and provide more biocompatibility. They get degraded and replaced or incorporated into a host’s tissue. They include- acellular dermal matrix, skin and bone substitutes, and injectables derived from decellularized mammalian tissues (of human and animal origin).
Here we will be discussing 1) Skin substitutes and 2) Bioprosthetic materials which include Acellular Dermal Matrices.
1) Skin substitutes
They are bioengineered alternative skin cover options. Three important components required for their formation are: (1) a cell source, (2) a ’tissue differentiation-inducing’ substance, and (3) a matrix.
- As a replacement for skin grafts in severe burns
- Chronic venous and diabetic ulcers
- Pressure sores (Dermagraft)
- Very expensive
- Not free available in India and other countries.
Various Available Skin Substitutes
💡 MNEMONIC – I D E A (with the order of DE interchanged)
2) Bioprosthetic Materials
The dermis is the most common source tissue- processed to remove cells, cellular debris, other potentially immunogenic components (epidermis is antigenic) without disrupting the native extracellular matrix- ECM (e.g., collagen, proteoglycan) architecture.
- Small intestinal submucosa (SIS)- Porcine (Biodesign)- First.
- Acellular dermal matrix (ADM)- Human (AlloDerm), Porcine
- Others: Bovine Bone, Pericardium (Veritas, Deerfield), and Fetal dermis (Surgimend, Primatrix)
- Resist infection
- Limit repair site adhesions
- Tolerate cutaneous exposure, usually without the need to remove the mesh.
- Remodel and regenerate (gradually being replaced with native host tissue) rather than become scarred and encapsulated by the body (promoted by the native extracellular matrix- ECM)
Small intestinal submucosa (SIS)- Porcine (Biodesign)
The submucosa of the small intestine provides mechanical strength to the intestine and is biochemically rich with a diverse extracellular matrix. The mucosal, serosal, and muscular layers of the small intestine are removed.
- Multiple types of hernia repair
- Dural repair
- Bladder reconstruction
- Stress urinary incontinence treatment
Human acellular dermal matrix- HADM (Alloderm, Allomax, FlexHD)
Made from donated allograft human dermis. The epidermis and subcutaneous tissue are removed and the dermis is processed, with either freeze-drying or chemical detergents, resulting in the collagen structure of the dermal matrix.
- Implant-based breast, abdominal wall, chest wall, and pelvic reconstruction
- Lip augmentation.
- Injectable– Micronized HADM (Cymetra)- Laryngoplasty, Soft-tissue filler.
Porcine acellular dermal matrix- PADM (CollaMend, Permacol, Strattice)
Based on the processing method used to inhibit the immunogenicity without degrading the ECM:
- 1st Generation- Cross-linked PADM– By chemical cross-linking of collagen fibers- leads to alteration of the ECM structure- inhibit cellular infiltration, revascularization, and matrix remodeling- gets encapsulated. (CollaMend, Permacol)
- Newer generation- Non-cross-linked PADM– By enzymatical removal of [galactose-α(1,3)-galactose] antigen, the major cause of the immune response– rapidly infiltrated with host cells and vessels. (Strattice)
- More abundant
- Easier to control the harvesting conditions
- Additional processing must occur to prevent an adverse immunogenic reaction when implanted in humans (since xenogenic)
- Neligan’s Plastic Surgery- Vol 1- Principles- 4Ed (2017)
- Plastic Surgery Secrets Plus- Weinzweig- 2Ed (2010)