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Stable In Vivo Integration of
Non-Biodegradable Polymer
Fabric Into New Dermal Tissue
Frederick Cahn
Themis Kyriakides
BioIntegrated Prosthetics Systems
(A Division of Biomedical Strategies LLC, La Jolla, CA)
BioIntegrated Prosthetics Systems
BioIntegrated Prosthetic
• A prosthetic device supported by a pylon that is
osteointegrated with skeletal bone as well as with
the dermal and epidermal layers of the skin.• Osteointegrated prosthetics have been developed by Branemark in
Sweden.
• Clinically demonstrated in over 100 patients
• Many advantages due to elimination of the conventional cuff
• Severe disadvantage of chronic inflammation and frequent infection.
• Surgical improvements have brought infection to a low level, but probably
not sufficient for routine clinical use.
BioIntegrated Prosthetics Systems
Biointegrated Prosthetic Device
BonePylon
StumpProblem Area
BioIntegrated Prosthetics Systems
Concepts for Transcutaneous Devices
• Antimicrobials
• Novel biomaterials or surface treatments to
promote epidermal cell adhesion
• Fibrous cuffs• Short term success on catheters
• None of these have enabled a permanent
transcutaneous solution
BioIntegrated Prosthetics Systems
Pendegrass and Blunn
• Pendegrass and Blunn (University College
London) studied the antler.• Collagen fibers radiate from the pedicle and integrate with the dermis.
• Added a perforated flange to the pylon to stabilize
the surrounding skin.
• Demonstrated this design in a goat model• Stable
• No marsupalization of the epidermis observed
• Initiated clinical studies on fingertips
BioIntegrated Prosthetics Systems
Pendegrass and Blunn Design
BioIntegrated Prosthetics Systems
Design Postulates for Transdermal
Biointegration
• Dermal Anchoring• Mechanically couple dermis to the device to prevent strain at the epidermal-device
junction (already demonstrated by Pendegrass and Blunn)
• Modulate mechanical compliance to avoid a concentration of stress in the skin
• Avoid scar tissue
• Closed wound physiology• Avoid foreign body reactions with the anchor components
• Healthy vascular dermal tissue will provide immune protection and support a
healthy epidermal barrier
• Non-inflammatory healing after implantation surgery• Yannas-Burke artificial skin provides non-inflammatory healing and regeneration of
dermal tissue without scar
• Lack of hair and skin appendages is an added advantage of artificial skin
BioIntegrated Prosthetics Systems
Artificial Skin of Yannas and Burke
A “neodermis” forms in thescaffold layer in 2 to 3 weeks
BioIntegrated Prosthetics Systems
Dermal Anchor Design
• Our initial dermal anchor design embeds a woven
fabric with engineered mechanical properties in
an artificial skin matrix.
Silicone Temporary Layer
Pylon
Porous Collagen-Glycosaminoglycan Resorbable Scaffold
Dermal Anchor
BioIntegrated Prosthetics Systems
Experimental Objectives
• Demonstrate that a dermal anchor fabric
embedded in artificial skin matrix will become
stably embedded in regenerated dermal tissue• Without disrupting the non-inflammatory healing process of artificial skin
• Without significant foreign body response to the fabric
• Identify biomaterials and geometries that
minimize foreign body reactions
• Use a proven small animal model that was used
for the preclincial studies that led to the clinically
successful artificial skin
BioIntegrated Prosthetics Systems
Full Thickness Guinea Pig Wound Model
Our histology is taken at 17days, before significantcontraction
Unlike human wounds,guinea pig wounds closeprimarily by contraction
BioIntegrated Prosthetics Systems
Guinea Pig Model
• Our model embeds experimental fibers or meshes in an artificial skin
scaffold
• The artificial skin composite device is implanted in an excised full
thickness wound bed
Silicone Temporary Layer
Porous Collagen-Glycosaminoglycan Resorbable Scaffold
Test Fibers or Mesh
panniculus carnosus
Guinea PigDermis
Epidermis
BioIntegrated Prosthetics Systems
Lab vs.
Commercial
Artificial
Skin at 17
days
Lab
Improved
Lab vs.
Commercial
Artificial Skin
at 17 days
Commercial Lab
Sutures
and
Carbon
Fibers at
17 days
BioIntegrated Prosthetics Systems
Mesh Woven from Polyester Yarn
100 X 400 X
BioIntegrated Prosthetics Systems
Conclusions
• Despite the inclusion of the mesh of polyester yarn, the
healing response was similar to that of control grafts
• The mesh appeared to integrate well in the collagenous
network
• There was minimal foreign body response to the mesh
• Thus, we were successful in generating artificial skin graft
containing an incorporated polyester yarn mesh that was
well-tolerated and stable in the guinea pig model.
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