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.