Hydrogels and use thereof in anastomosis procedures
Inventors
Schneider, Joel • Brandacher, Gerald • Smith, Daniel • Brat, Gabriel • Grahammer, Johanna
Assignees
Johns Hopkins University • US Department of Health and Human Services
Publication Number
US-10086108-B2
Publication Date
2018-10-02
Expiration Date
2036-01-22
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Abstract
This disclosure provides novel hydrogels that can undergo multiple gel-sol transitions and methods of making and using such hydrogels, particularly in anastomosis procedures. The peptide hydrogels comprising a fibrillar network of peptides that are in an amphiphilic β-hairpin conformation. The peptides comprise photo-caged glutamate residues with a neutral photocage that can be photolytically selectively uncaged to disrupt the fibrillar network and trigger an irreversible gel-sol phase transition of the hydrogel. Isolated peptides for making the disclosed hydrogels are provided, as are methods of using the peptide hydrogels in anastomosis procedures.
Core Innovation
This invention provides novel peptide-based hydrogels that undergo multiple consecutive gel-sol and sol-gel phase transitions. The peptides form a fibrillar network adopting an amphiphilic β-hairpin conformation comprising a β-turn, two β-strands, a hydrophobic face, and a hydrophilic face. These hydrogels exhibit shear-thin/recovery rheological properties, enabling them to be delivered by syringe in a low viscosity state and to self-heal into a solid-like gel within the lumen of collapsed vessels, thereby mechanically supporting and distending the vessels to facilitate suturing in anastomosis procedures.
The peptides include photo-caged glutamate residues with a neutral photocage, such as 4-methoxy-7-nitroindolinyl-glutamate, located on the hydrophobic face proximate to a glycine residue on the opposing β-strand. This arrangement allows incorporation of the neutral photocage without disrupting initial hydrogel formation. Upon selective irradiation at an appropriate wavelength (e.g., 365 nm), the photocage is photolytically uncaged revealing the negatively charged glutamate side chain, which disrupts hydrophobic interactions within the fibrillar network, triggering an irreversible gel-sol phase transition that dissolves the hydrogel and restores vessel patency.
The problem being addressed is that current methods for anastomosis, especially in small or fragile vessels, face challenges due to vessel contraction or collapsed ends that render suturing difficult and limit microsurgical procedures. Existing degradable stents and tissue adhesives either depend on temperature control or exhibit slow dissolution, which impedes utility. There is a need for materials that can quickly support vessels in an open configuration during suturing, and that can be removed without relying on temperature or slow dissolution.
Claims Coverage
The patent includes multiple independent claims covering peptide hydrogels with unique structural and functional properties, isolated peptides that form such hydrogels, and methods of performing anastomosis using these hydrogels. Six independent claims are identified addressing these aspects.
Peptide hydrogel capable of multiple phase transitions
The hydrogel comprises a fibrillar network of peptides in an amphiphilic β-hairpin conformation that includes a β-turn, a first β-strand bearing photo-caged glutamate residues with a neutral photocage, and a second β-strand bearing a glycine residue. The photocaged glutamate and glycine sidechains are proximal on the hydrophobic faces, enabling assembly by hydrophobic interactions. The hydrogel undergoes a reversible gel-sol phase transition upon shear stress and an irreversible gel-sol phase transition upon photolytic uncaging of the glutamate residues that disrupts the fibrillar network.
Disruption of hydrophobic interactions by uncaging glutamate residues
Uncaging the photocaged glutamate residues exposes negative charges that disrupt hydrophobic interactions stabilizing the fibrillar peptide network, triggering an irreversible gel-sol transition of the hydrogel.
Physical and chemical parameters of the hydrogel
The hydrogel maintains a storage modulus greater than 40 Pascal without shear, includes about 20 mM to 400 mM NaCl, a pH from about 7.0 to 9.0 (e.g., about 7.4), and peptide concentrations from about 0.25% to 4.0% w/v (e.g., 1% to 2% w/v). The peptide length ranges from 10 to 75 amino acids.
Specific peptide sequences
Peptides forming the hydrogel include sequences selected from consensus peptides APCC1 to APCC8a or specific peptides APC1 to APC23a, where the photocaged glutamate residue is typically a 4-methoxy-7-nitroindolinyl-glutamate.
Isolated peptides forming amphiphilic β-hairpin conformation and hydrogels
Isolated peptides that fold into an amphiphilic β-hairpin conformation in given aqueous conditions (150 mM NaCl, pH 7.4, 25° C.) and include a photocaged glutamate and glycine with proximal sidechains on the hydrophobic face can form hydrogels with fibrillar networks. These hydrogels exhibit reversible gel-sol transitions under shear and irreversible transitions upon photolysis.
Method of performing anastomosis using peptide hydrogels
The method comprises filling the lumen of severed vessel ends with the hydrogel to maintain an open configuration, apposing and anastomosing the vessel ends, and subsequently irradiating with light of a preselected wavelength to uncage glutamate residues and cause gel-sol transition to low viscosity gel, allowing blood flow to disperse the hydrogel and restore vessel patency.
In summary, the claims cover peptide hydrogels formed from amphiphilic β-hairpin peptides containing photocaged glutamate residues that enable multiple phase transitions, specific peptides capable of forming such hydrogels, and a method of vascular anastomosis employing these hydrogels to support vessels and facilitate their suturing and removal of the hydrogel post-procedure via photolytic disruption.
Stated Advantages
The hydrogels enable rapid and easy application via syringe, supporting collapsed vessels in an open configuration to facilitate suturing.
Shear-thinning and self-healing properties allow delivery through narrow needles and immediate recovery inside the vessel lumen.
The hydrogels are optically transparent, permitting suturing directly through the gel medium.
Photolytic uncaging of glutamate residues allows efficient and controlled gel dissolution without dependency on temperature or slow dissolution.
The hydrogel avoids remaining residues causing thrombosis and allows restoration of blood flow with demonstrated vessel patency in vivo.
Documented Applications
Use as temporary intraluminal stents during anastomosis procedures of blood vessels, lymphatic vessels, and ducts.
Facilitating end-to-end suturing of severed vessels ranging in diameter from about 50 μM to 10 mM, including mouse femoral artery models.
Application for vascular/microvascular reconstructive surgeries requiring micro-scale anastomosis.
Interested in licensing this patent?