Bioresorbable silk grafts for small diameter vascular tissue engineering applications: In vitro and in vivo functional analysis

Progressive Reinvention or Destination Lost? Half a Century of Cardiovascular Tissue Engineering

“…As such, any tissue engineering approach that justifies the word “engineering” will require animal models which allow a rational and mechanistic exploration of key components of the “endogenous tissue restoration” expected at the clinical destination site. A myriad of fascinating modern scaffold materials for instance has been investigated under in-vivo conditions which did not emulate key cornerstones of the human situation ranging from thermoplastic polymers such as degradable polyurethanes ( 394 ); poly-e-caprolactone (PCL)–alone or in combination with poliglecaprone ( 395 ), with polydioxanone ( 396 ) or with Gelatine ( 397 )- “supramolecular”: ureic-pyrimidone-modified polycaprolactone ( 158 , 398 ) also in combination with ureic pyrimidone PEG ( 398 ) to thermoset polymers such as polyglycerol-sebacate (PGS) ( 399 ) or nanofiber scaffolds of naturally occurring polymers such as polysaccharides (cellulose) ( 400 – 402 ); hyaluronic acid ( 343 ); silk ( 385 , 403 ), collagen ( 404 ), Elastin-like blends ( 405 , 406 ), fibrin ( 407 ), or collagen-elastin ( 408 ). For none of these materials do we have an answer to two of the critical questions asked at the beginning: (1) as scaffolds, do they allow transmural endothelialisation or alternatively facilitate true fall-out endothelialisation and (2) given the absence of trans-anastomotic neointimal outgrowth in man: is scaffold degradation (eg., by blood borne inflammatory cells) balanced against neo-tissue formation to prevent a premature structure-loss in patients?…”

Challenges and strategies for in situ endothelialization and long-term lumen patency of vascular grafts

“…Furthermore, vascular graft PolyMaille (Perouse Medical, France) with collagen coating is already available. Some other natural polymers, like elastin [ 109 ], silk fibrin [ 110 , 111 ], are also alternative for vascular graft application. These polymeric coatings can provide non-specific binding sites not only for EC adhesion, but also for other blood cells like platelets, white cells, and SMCs, which may induce thrombogenesis and IH.…”

Harnessing Mechanosensation in Next Generation Cardiovascular Tissue Engineering

“…Concerning materials, one of the most investigated for manufacturing vascular structures is silk protein component fibroin [ 132 , 133 ]. Compared to other biodegradable materials, silk is a naturally anti-thrombogenic protein [ 134 ] that does not elicit severe inflammatory responses [ 135 ].…”

“…In such a case, a bioreactor is often used to achieve mechanical maturation of the vessel constructs by applying specific flow conditioning regimes able to tailor the blood vessel adaptation to the required (e.g., arterial vs. venous) hemodynamic performance. A second approach consists of transplanting cell-free tubular scaffolds in vivo, exploiting the ability of the recipient body to colonize the grafts with own cells and direct in situ cellularization ( Figure 3 ) [ 133 ].…”