Xenograft soft tissue implants and methods of making
View Patent ↗The present application is directed to the field of implants comprising soft tissue for use in implantation in humans. The soft tissue implants of the present application are preferably obtained from xenograft sources. The present application provides a chemical process that sterilizes, removes antigens from and/or strengthens xenograft implants. The present techniques yield soft tissue implants having superior structural, mechanical, and/or biochemical integrity. The present application is also directed to processes for treating xenograft implants comprising soft tissues such as dermis, and to implants produced by such processes.
1. A method for the preparation of a graft from porcine dermis comprising the following steps:
a. proving a porcine dermis having a native dermal matrix,
b. treating said dermis with an aqueous, alkaline sodium sulfide solution for at least 1 hour, wherein said solution comprises 0/01 to 1.5% by weight of sodium sulfide and 0.001 to 0.5 M sodium hydroxide and said solution has a pH greater than 10,
c. once or several times, treating the dermis with a saline solution,
d. once or several times, treating the dermis with an aqueous hydrogen peroxide solution, and
e. dehydrating the dermis via solvent dehydration, wherein said solvent dehydration step comprises starting as a lower concentration of solvent and finishing a higher concentration of solvent;
wherein the graft is non-crosslinked and the histoarchitecture of the native dermal matrix is maintained.
2. The method of claim 1 , wherein said dermis in step b) is treated in an aqueous sodium sulfide containing solution for 1 to 48 hours, with a solution volume in milliliters that is 5 to 15 times the mass of the dermis in grams.
3. The method of claim 1 , wherein said dermis in step c) is treated two to ten times with the saline solution, wherein the saline solution comprises 1 to 50 wt-% salt, and wherein the salt is an alkali metal or alkaline earth metal, selected from the group consisting of sodium chloride, potassium chloride, lithium chloride, magnesium chloride and calcium chloride.
4. The method of claim 1 , wherein the dermis in step d) is treated two to five times with the aqueous hydrogen peroxide solution, wherein the aqueous hydrogen peroxide solution comprises 1 to 10 wt-% of hydrogen peroxide, with optional rinsing between each treatment.
5. The method of claim 1 , wherein the dermis in step e) is dehydrated by treating from two to ten times with an organic solvent selected from the group consisting of acetone, methanol, ethanol and isopropyl alcohol.
6. The method of claim 1 , wherein providing the dermis in step a) comprises the steps of: a1) cleaning the skin of slaughtered pigs with detergent-containing water at a temperature of not more than about 40° C., a2) removing the skin from the back portion of the pig, a3) removing the bristles from the skin provided in step a2), and removal of the subcutaneous tissue and the epidermis from the dermis using a splitting machine.