Development and manufacture of an investigational human living dermal equivalent (ICX-SKN).
OBJECTIVE
To design and manufacture an investigational living skin graft replacement (ICX-SKN) that is able to incorporate into the host, providing healing by primary intent without the need for a second intervention.


METHODS
The ICX-SKN skin graft replacement has been designed as an allogeneic dermal substitute comprising an extracellular matrix composed largely of human collagen and human dermal fibroblast cells (HDFs). ICX-SKN is first formed by casting a provisional matrix of fibrin, into which HDFs are seeded. Through a process of maturation, HDFs are induced to lay down collagen and other extracellular matrix materials and, as the construct matures, the original fibrin is largely replaced by collagen, which provides tensile strength and flexibility to the construct. In order to design a product and manufacturing system that lends itself to large-scale production the process was developed as a discontinuous process consisting of four stages: 1. batch casting and maturation of the initial construct (pSKN), 2. freeze-drying of pSKN to produce a second intermediate (dSKN), 3. sterilization by gamma-irradiation of dSKN to produce a third intermediate (sSKN), and finally, 4. repopulation of sSKN by fresh HDFs to produce the final product, ICX-SKN skin graft replacement. Preliminary characterization of ICX-SKN and its application in a preclinical model are described.


RESULTS
The 7-week maturation period resulted in a construct (pSKN) with robust handling properties, which was composed mainly of human collagen I. Following development of a process for freeze-drying and subsequent sterilization, the matrix was successfully repopulated with fresh HDFs. In addition, it was demonstrated that human keratinocytes attached and differentiated on the matrix. Application of human keratinocytes to the repopulated constructs (ICX-SKN) resulted in expression of markers of basement membranes that was largely dependent on the presence of living HDFs on the constructs. ICX-SKN graft replacements applied to excision wounds in mice healed and were rapidly re-epithelialized.


CONCLUSIONS
ICX-SKN has been developed as a platform product that can be used as a skin graft replacement and the process by which it is manufactured has been designed for the product to be available to the end-user off-the-shelf and for ease-of-use in practice.
Flasza
Marzena
M
Intercytex Ltd., Innovation House, Crewe Road, Manchester M23 9QR, UK.
Kemp
Paul
P
Shering
David
D
Qiao
Jizeng
J
Marshall
Damian
D
Bokta
Ausha
A
Johnson
Penny A
PA
D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D001709:Biotechnology / Q000379:methods; D020405:Dermis / Q000378:metabolism / Q000502:physiology*; D004817:Epidermis / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism; D006801:Humans; D051379:Mice; D012038:Regeneration; D012867:Skin / Q000473:pathology*; D016038:Skin Transplantation / Q000295:instrumentation* / Q000379:methods; D017768:Skin, Artificial; D014945:Wound Healing
D001672:Biocompatible Materials; D005340:Fibrinogen