Silk fibroin microtubes for blood vessel engineering

Abstract

Currently available synthetic grafts demonstrate moderate success at the macrovascular level, but fail at the microvascular scale (<6mm inner diameter). We report on the development of silk fibroin microtubes for blood vessel repair with several advantages over existing scaffold materials/designs. These microtubes were prepared by dipping straight lengths of stainless steel wire into aqueous silk fibroin, where the addition of poly(ethylene oxide) (PEO) enabled control of microtube porosity. The microtube properties were characterized in terms of pore size, burst strength, protein permeability, enzymatic degradation, and cell migration. Low porosity microtubes demonstrated superior mechanical properties in terms of higher burst pressures, but displayed poor protein permeability; whereas higher porosity tubes had lower burst strengths but increased permeability and enhanced protein transport. The microtubes also exhibited cellular barrier functions as low porosity tubes prevented outward migration of GFP-transduced HUVECs, while the high porosity microtubes allowed a few cells per tube to migrate outward during perfusion. When combined with the biocompatible and suturability features of silk fibroin, these results suggest that silk microtubes, either implanted directly or preseeded with cells, are an attractive biomaterial for microvascular grafts.

Electrospun Poly(lactide-co-glycolide-co-3(S)-methyl-morpholine-2,5-dione) Nanofibrous Scaffolds for Tissue Engineering

“…The yields of the copolymerization were in the range of 75%-85%. The MMD contents in P(LA-co-GA-co-MMD) 1 , P(LA-co-GA-co-MMD) 2 and P(LA-co-GA-co-MMD) 3 copolymers were estimated to be 5.5%, 13.0% and 17.4%, respectively. And the number-averaged molecular weights and polydispersity indexes of copolymers were in the range of 4.08ˆ10 4 adding 150 µL dimethyl sulfoxide (DMSO) and vibrated slightly for 10 min, and then 100 µL solution was transferred into a new 96-well plate.…”

“…The Schlenk was finally sealed under dry nitrogen and was immersed into an oil bath previously heated to 120˝C for 24 h. The copolymer was dissolved in chloroform and precipitated in n-hexane, repeated this process for three times, and dried at room temperature for 24 h under vacuum. Finally, the copolymers named as P(LA-co-GA-co-MMD) 1 , P(LA-co-GA-co-MMD) 2 and P(LA-co-GA-co-MMD) 3 were obtained, where the subscript 1, 2, and 3 stand for different LA/GA/MMD contents in copolymers as described in Table 1. …”

“…PLGA, P(LA-co-GA-co-MMD) 1 , P(LA-co-GA-co-MMD) 2 , and P(LA-co-GA-co-MMD) 3 were dissolved in chloroform (CHCl 3 ) and N,N-dimethylformamide (DMF) solvent in 7:3 volume ratio to prepare 20 w/v % spinning solution separately.…”

“…The scaffolds were treated with a 70% ethanol solution overnight and then stored in sterile filtered PBS solution before implantation. These rats were randomly assigned to four groups (two specimens in each rat) to implant PLGA, P(LA-co-GA-co-MMD) 1 , P(LA-co-GA-co-MMD) 2 , and P(LA-co-GA-co-MMD) 3 scaffolds. After seven days, the scaffolds were explanted and fixed in 10% buffered formalin solution for two days.…”

“…The PLGA and P(LA-co-GA-co-MMD) copolymers were synthesized by ROP of LA, GA,s and MMD using Sn(Oct) 2 as catalyst. As shown in Table 1, the contents of LA, GA and MMD in copolymers and the molecular weights of copolymers were estimated by 1 H NMR and GPC, respectively.…”