Skin Substitutes (Biological materials)

0
66
(Last Updated On: June 14, 2018)

Skin Substitutes- Plarecon- header

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. 

Uses

  1. As a replacement for skin grafts in severe burns
  2. Chronic venous and diabetic ulcers
  3. Pressure sores (Dermagraft)

Problems

  1. Very expensive
  2. Not free available in India and other countries.

Various Available Skin Substitutes

  Origin Layers Comments
1. Integra
Synthetic

1. Upper- Silicone sheet– temporary epidermis
2. Lower dermal- Bovine collagen and GAG matrix (Replaced by autogenous cells)

  • Require SSG after 10-14 days.
  • More infection
  • Good wound healing time.
2. Epicel
Autogenous

Cultured autogenous
keratinocytes (2-8 layers thick)

  • Needs 3 weeks time for the cells to grow.
3. Dermagraft

Allogeneic dermis

Vicryl (polyglactin) mesh
seeded with neonatal fibroblasts– produce collagen, GAGs, fibronectin, other growth factors.

  • Requires SSG- increased ‘take’.
  • Infection, healing time- similar to allografts.
4. Apligraf 

Allogeneic composite

1. Upper- Neonatal keratinocytes
2. Lower dermal- Collagen seeded with fibroblasts from neonatal foreskin (Replaced by autogenous cells).

  • SSG to improve cosmesis
  • has to be applied “fresh” 
  • shelf-life of 5 days at room temp.

💡 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.

Includes

  • 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)

Advantages

  1. Resist infection
  2. Limit repair site adhesions
  3. Tolerate cutaneous exposure, usually without the need to remove the mesh.
  4. 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.

Uses

  1. Multiple types of hernia repair
  2. Dural repair
  3. Bladder reconstruction
  4. 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.

Uses

  1. Implant-based breast, abdominal wall, chest wall, and pelvic reconstruction
  2. Lip augmentation.
  3. Injectable– Micronized HADM (Cymetra)- Laryngoplasty, Soft-tissue filler.

 

Porcine acellular dermal matrix- PADM (CollaMend, Permacol, Strattice)

Types

Based on the processing method used to inhibit the immunogenicity without degrading the ECM:

  1. 1st Generation- Cross-linked PADMBy chemical cross-linking of collagen fibers- leads to alteration of the ECM structure- inhibit cellular infiltration, revascularization, and matrix remodeling- gets encapsulated. (CollaMend, Permacol)
  2. Newer generation- Non-cross-linked PADMBy enzymatical removal of [galactose-α(1,3)-galactose] antigen, the major cause of the immune response– rapidly infiltrated with host cells and vessels. (Strattice)

Advantages

  1. More abundant
  2. Easier to control the harvesting conditions
  3. Additional processing must occur to prevent an adverse immunogenic reaction when implanted in humans (since xenogenic)

 

Bibliography

  1. Neligan’s Plastic Surgery- Vol 1- Principles- 4Ed (2017)
  2. Plastic Surgery Secrets Plus- Weinzweig- 2Ed (2010)
Skin Substitutes (Biological materials)
5 (100%) 3 votes

Leave a Comment/ Suggestion

This site uses Akismet to reduce spam. Learn how your comment data is processed.