Amniotic Membrane Allografts
The amniotic membrane is a semi-transparent and flexible membrane covering the upper cavity of the placenta. During foetal development, it acts as an immunologically privileged protective barrier.
It consists of three layers: a shiny, non-adherent outer surface composed of a single layer of epithelium; a basal membrane containing thick collagen fibres; and an inner surface composed of a matte, pitted, and adhesive avascular stromal matrix.
Mesenchymal stem cells are found on the outermost surface of the membrane. It contains numerous growth factors, steroid hormones (oestrogen, progesterone), hydrolytic enzymes, oxidation-reduction enzymes, secondary enzymes, and many other factors.
The Amniotic Membrane utilises the growth factors and enzymes necessary to support healing and provide mechanical protection.
It initiates epithelialisation by forming a matrix for cell migration and proliferation. It prevents epithelial cell differentiation and apoptosis. It ensures basal epithelial cell adhesion.
It inhibits inflammation and angiogenesis, reduces pain, and exhibits a bacteriostatic effect. It acts as a natural barrier in the wound area. It exhibits scar-preventing and neurotrophic effects.
When used as a biological patch, the amniotic membrane consists of a combination of tissues and cells that play a pioneering role in the regrowth of soft tissue and aid in wound healing.
Histological Layers of the Fetal Membrane and Their Contents
Amnion
Basal Membrane: Type 3, 4, 5 collagens, laminin, fibronectin, nidogen
Compact Layer: Type 1, 3, 5, 6 collagens, fibronectin
Fibroblast Layer: Type 1, 3, 5 collagens, laminin, fibronectin, nidogen
Spongy Layer: Type 1, 3, 5 collagens, proteoglycan
Chorion
Reticular Layer: Type 1, 3, 4, 5, 6 collagens, proteoglycan
Basal Membrane: Type 4 collagen, fibronectin, laminin
Trophoblast
Content and Functions
The functions of Growth Factors (GF), Enzymes and Hormones found in the structure of the amniotic membrane are as follows.
REGENERATION and REPAIR
- Epidermal growth factor (EGF)
- Vascular Endothelial Growth Factor (VEGF)
- Keratinocyte Growth Factor (KGF)
- Fibroblast Growth Factor (FGF)
- Hepatocyte Growth Factor (HGF)
- Platelet-derived Growth Factor (PDGF)
- Transforming Growth Factor Alpha & Beta
(TGF & TGF) - Angiotensin, Interleukin 8 (IL-8)
SCAR AND FIBROSIS PREVENTATIVE
- Transforming Growth Factor Beta (TGFβ)
- Hepatocyte Growth Factor (HGF)
- Interleukin 10 (IL-10)
ANTI-INFLAMMATORY
- Interleukin 10 (IL-10)
- Interleukin 1 Receptor Antagonist (IL-1RA)
- Prostaglandin 2 (PGE2)
ANTIBACTERIAL
- Cathelicidin
- Defensins
ANTIMICROBIAL
- Elafin (SCALP)
- Secretory Leukocyte Proteinase Inhibitor (SLPI)
- Accelerates Epithelialisation
- Relieves Pain
- Enhanced Graft Tolerance
- Antimicrobial Activity
- Anticancer Effect
Areas of Use
Ophthalmology
Promotes rapid epithelialisation on corneal and conjunctival surfaces. Reduces inflammation and scar tissue.
Conjunctival Repairs
- Chemical/thermal burns,
- Pterygium surgery,
- Periorbital surface neoplasms,
- Bleb leakage,
- Entropion correction,
- Filtering surgery,
- Conjunctival chalazion,
- Symblepharon release,
- Sclerosing conjunctivitis,
- Socket repair.
Corneal Surface Repairs
- Bullous keratopathy,
- Refractory epithelial disorders, Non-healing corneal ulcer,
- Partial/total limbal stem cell deficiency,
- Scleral erosion Ocular cicatricial pemphigoid,
- Stevens-Johnson syndrome.
Reconstruction of the Conjunctival Surface Following Removal of Large Lesions (without conjunctival autograft)
- Tumour
- CIN
- Conjunctival calcification/SLK
- Scar or Symblepharon
- LOGIC Syndrome
- Pterygium
- Glaucoma bleb revision
- Scleromalacia
- Scleral erosion
Wound and Burn Treatments
Amniotic Membrane,
- Suitable for use to reduce peripheral wound-related amputation and mortality,
- Accelerate wound healing,
- Relieve pain,
- Improve quality of life.
- The mesenchymal stem cells, growth factors and enzymes contained within accelerate dermal regeneration, contributing to wound closure.
- By regulating the inflammatory environment, it stimulates the formation of well-vascularised matrix granulation tissue.
- It accelerates keratinocyte migration and prevents apoptosis in healing wound cells.
- Mesenchymal stem cells also accelerate healing in diabetic tissues, preventing the formation of non-healing ulcers.
Urological / Urogenital Surgery
Penile Augmentation (Preclinical)
In a study conducted using urethroplasty in a rabbit model, promising results were obtained in terms of tissue healing, biocompatibility, and structural integrity. It is an important preliminary study demonstrating the potential of alternative biomaterial combinations for penile reconstruction surgery in humans.
Penile Implantation
Amniotic membrane allografts placed within the surgical field accelerate the healing process. They improve pain management and allow for earlier activation of the implant.
Cervical and Vaginal Atresia or Agenesis
Amniotic membrane can be successfully used in the reconstruction of cervical and vaginal structures. In cases of cervicoplasty and vaginoplasty, excellent epithelialisation and patency of the cervix and vagina are achieved.
Complex Vaginal Mesh Erosion
The use of amniotic membrane in the treatment of complex vaginal mesh erosion, where conservative or primary surgical revisions have failed, is a method that contributes to complication-free and functional healing. It constitutes an economical and effective treatment alternative.
Laparoscopic Prostatectomy
The amniotic membrane placed on neurovascular bundles (NVBs) during RALP has positive effects on functional and oncological outcomes. It accelerates the recovery of potency and continence.
Urethral Reconstruction
Amniotic/chorionic grafts, used in the repair of urethral strictures, accelerate tissue healing and reduce scar formation.
Peyronie’s Surgery
In the surgical treatment of this disease, characterised by plaque formation in the penis, grafts fill the voids created after plaque removal, preserving the structural integrity of the penis.
Bladder Repair
Used in the repair of damage to the bladder wall, they support tissue regeneration and restore the bladder’s functional capacity.
Testicular and Scrotal Surgery
In cases of tissue loss in the testicular or scrotal region, grafts are effective in replacing the missing tissue and accelerating healing.
Brain, Spinal Cord and Nerve Surgery
Duraplasty
The amniotic membrane allograft is known to be as effective and safe an alternative as the temporal muscle fascia autograft in duraplasty procedures. With low complication rates, it is a promising biomaterial for dural repair in neurosurgery.
Peripheral Nerve Injuries
With its biocompatible, semi-permeable, flexible, and durable structure, the amniotic membrane exhibits good barrier properties. Used as a scaffold, the amniotic membrane plays important roles in neural regeneration. All studies in the literature provide increasing evidence regarding the biological properties of the amniotic membrane and peripheral nerve tissues and human amniotic membrane transplantation for the repair of peripheral nerve damage.