Tissue-engineered constructs
Inventors
Dahl, Shannon L. M. • Niklason, Laura E. • Blum, Juliana • STRADER, Justin T. • Tente, William E. • Prichard, Heather L. • LUNDQUIST, Joseph J.
Assignees
Publication Number
US-9556414-B2
Publication Date
2017-01-31
Expiration Date
2032-01-06
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Abstract
The present invention provides constructs including a tubular biodegradable polyglycolic acid scaffold, wherein the scaffold may be coated with extracellular matrix proteins and substantially acellular. The constructs can be utilized as an arteriovenous graft, a coronary graft, a peripheral artery bypass conduit, or a urinary conduit. The present invention also provides methods of producing such constructs.
Core Innovation
The invention provides tubular biodegradable polyglycolic acid scaffolds characterized by a uniform density of about 45 mg/cc to about 75 mg/cc and uniform thickness, which can be coated with extracellular matrix proteins and are substantially acellular. The constructs may include non-biodegradable polyethylene terephthalate supports at each end to facilitate cell attachment and growth. These constructs are designed for various uses such as arteriovenous grafts, coronary grafts, peripheral artery bypass conduits, fallopian tube replacements, and urinary conduits.
The invention addresses a significant need for vascular grafts when a patient's own blood vessels are unavailable due to prior harvest or disease. Synthetic grafts currently used, like polytetrafluoroethylene (PTFE) grafts, have poor patency rates and are prone to complications such as infection, thrombosis, and intimal hyperplasia. Existing tissue-engineered vascular grafts require long culture times and are costly, limiting their clinical use. Hence, there is a need for rapidly available, reliable, and cost-effective tissue-engineered constructs that function long term with minimal side effects in vivo.
Methods for producing the constructs involve providing a biodegradable polyglycolic acid sheet of defined density and thickness, wrapping it around a mandrel, entangling fibers at the seam to form a uniform tubular scaffold, treating it to remove heavy metals and increase degradation, seeding human cells at low passages on the scaffold to promote secretion of extracellular matrix proteins, and subsequently decellularizing the construct to produce a substantially cell-free, immune- and calcification-resistant tubular graft. The constructs have mechanical properties comparable to native vessels, are impermeable to fluid leakage at physiological pressures, and resist in vivo complications such as intimal hyperplasia and dilatation.
Claims Coverage
The claims include two independent claims focusing on methods of producing tubular biodegradable polyglycolic acid constructs with defined properties and cell culture conditions.
Uniform biodegradable polyglycolic acid tubular construct
A tubular biodegradable polyglycolic acid construct having an inner diameter of about 3 mm to about 6 mm, comprising entangled PGA fibers with a density of about 45 mg/cc to about 75 mg/cc uniformly distributed across the scaffold.
Low passage human cell seeding and culturing conditions
Seeding human cells at passage 6 or less on the PGA construct and culturing under conditions that promote extracellular matrix protein secretion, including specific human serum percentages (about 11% to 30% for first 2–6 weeks and about 1% to 10% for at least additional 4 weeks), optionally in medium containing high glucose, insulin, bFGF, and EGF.
Decellularization producing substantially acellular, immune- and calcification-resistant grafts
Decellularizing the cultured construct to achieve substantially less than 5% intact cells (less than 1% in some claims) using detergents lacking sodium dodecyl sulfate and optionally an endonuclease, providing resistance to intimal hyperplasia and calcification.
Control of polyglycolic acid degradation and extracellular matrix thickness
Degrading the polyglycolic acid within the construct so it comprises less than 33% of the cross-sectional area, and ensuring the extracellular matrix protein thickness is greater than about 200 micrometers at the thinnest portion.
Removal of heavy metal contaminants
Scouring the tubular PGA construct to remove trace amounts of heavy metals including aluminum, barium, calcium, iodine, lanthanum, magnesium, nickel, potassium and zinc prior to or during fabrication.
The claims collectively cover a method to produce a tubular biodegradable polyglycolic acid scaffold with uniform density and dimensions, seeding and culturing with low passage human cells under defined media conditions, decellularizing to yield an acellular, immune- and calcification-resistant extracellular matrix-rich construct with reduced polymer content, and including treatment steps to remove contaminants and modify degradation.
Stated Advantages
The constructs provide readily available, rapidly produced tissue-engineered grafts without the long wait times and high costs associated with autologous grafts.
They have good mechanical properties, including burst pressures over 2000 mm Hg and suture retention strengths greater than 120 g, matching or exceeding native vascular tissue attributes.
The constructs are resistant to infections, immune response, intimal hyperplasia, aneurysmal dilation, and calcification upon implantation in vivo.
They are stable, capable of being stored at about 2° to 30° C. for months to years without loss of function.
The absence of living cells and minimal residual polymer content reduces immunogenicity and promotes integration with host tissue.
Documented Applications
Use as arteriovenous grafts for hemodialysis access in patients with end stage renal disease.
Use as coronary grafts for bypassing blocked coronary arteries.
Use as peripheral artery bypass conduits for treating peripheral arterial disease.
Use as urinary conduits for diversion of urine following cystectomy, avoiding bowel harvest complications.
Use as fallopian tube replacements to address fallopian tube scarring and infertility.
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