Table 5.

Polysaccharide-based scaffolds for tissue-engineered heart valves.

Scaffold Types	Preparation Methods	Results	Ref.
Chitosan-Based Scaffolds
CH films	Casting method to form films; Adsorption of protein sol. on CH films (4 °C, overnight).	CH films: FI/SMCs is less spread and more elongated; CH/AP: modest VECs growth, altered elongated morphology, low spreading; CH/COL IV composites: enhanced VECs growth, superior cell morphology.	[164]
CH/AP
CH/COL composites
(bFGF-CH-P4HB)/DPAV hybrid scaffolds	Coating DPAV with bFGF-CH-P4HB by electrospinning technique (20 kV, room temp.)	bFGF-CH-P4HB fibers form membranes with uniform thickness, firmly attached on DPAV surface; bFGF has a positive effect on the MSCs proliferation.	[165]
CH/BP scaffolds	Immersion of BP tissues in CH/H2CO3 sol. (pH 3, 2 h, 30 MPa, room temp.)	CH/BP are less rigid and the risk factor of fatigue failureis reduced; Calcification and bacterial strains adhesion are attenuated; In vivo: no inflammatory reaction, after 4 months of implantation in rats.	[166]
CH-PU-GEL nanofibrous scaffolds	Electrospinning technique (16 to 20 kV, room temp.)	OCAs adhered preferentially on CH-GEL-PU, are flattened, spread across the surface and have cobblestone morphology; able to withstand shear-stresses ranging from 0.062 to 0.185 N/m2 for up to 3 h;	[167]
CH fibers with immobilized HEP	Extrusion method; HEP immobilization with EDC	Crosslinking degree influences fiber diameters, strength and stiffness; CH-HEP promotes VIC attachment and growth (cell viability ~ 95%, 10 days).	[168]
CH-PCL/DBP biohybrid scaffolds	Electrospinning technique (27–32 °C, 15 kV)	hVICs viability on CH-PCL/DBP (A&R) ~ 90%; Biohybrid (A) has better uniaxial mechanical properties and higher alignment of hVICs compared to a randomly electrospun sample (B).	[169]
Hyaluronic Acid-Based Scaffolds
Me-HA, Me-HA/PEG-DA hydrogels	Photopolymerization (UV light, 5 mW/cm2, 3 min, photoinitiator)	Degradation rate: Me-HA/PEG-DA—1 week; Me-HA—2 days; VICs remain viable following photopolymerization; high proliferation after exposure to LMW HA degradation products.	[170]
(Me-HA+CD34)/Me-Gel hydrogels	Photopolymerization (UV light, 180 s, 5.5 mW/cm2); CD34 immobilization by EDC/NHS.	Increasing CD34 conc. increases EPC attachment (25.3 ± 5.3 EPCs/mm2 at 10 μg/mL; 52.2 ± 5.0 EPCs/mm2 at 25 μg/mL); (Me-HA+CD34)/Me-Gel promoted cell elongationand higher spreading.	[171]
SilylHA-CTA/LLDPE IPNs	Silylation of HA-CTA; LLDPE films swollen in silylHA-CTA/xylene (50 °C/1 h).	HA/LLDPE exhibit lower contact angles and less blood clotting than LLDPE alone, which led to considerable thrombus formation; PHVs showed acceptable values for RF (4.77 ± 0.42%) and EOA (2.34 ± 0.5 cm2).	[172,173]
HA-LLDPE IPNs/CoCr-MP35N stent	Swelling process was used to obtain IPNs; fixing by PP sutures on the stent frame.	Hemodynamic parameters (EOA, RF, PI) have values comparable with those of commercial transcatheter valves; Turbulent flow tests show a decrease of RSS at each cardiac phase.	[174]
Me-HA/Me-Gel MOHA/Me-Gel hybridhydrogels	Molding technique and exposure to UV light (2 mW/cm2; 5 min)	Me-Gel stimulates VICs spread and migration from spheroids; Cell circularity was much lower in low stiffness hydrogels than in stiffer ones; VICs have a spindle-like morphology only in hydrogels with Me-Gel.	[175]
Me-HA/Me-Gel/PGS-PCL hybrid hydrogels	Immersion of electrospun PGS-PCL into hydrogel; Photocrosslinking (UV light, 45 s, 2.6 mW/cm2).	MVICs have an initial rounded shape and low spread; MVICs are predominantly spread over the surface of PGS-PCL fibers only; 21 days: MVICs spread is complete into hybrid hydrogels, with non-homogenous distribution at different depths.	[176]
Cellulose-Based Scaffolds
CA coatings for metallic valves	Electrospinning technique; Surface functionalization with RGD and YIGSRG	CA coatings promote cardiac cell growth on valve surface; CA ensures the control of endothelialization and reduction of thrombosis.	[12]
CNF/PU films nanocomposites	Film-stacking method; Compression molding	Prosthetic valves have good biological durability, fatigue resistance and hemodynamics properties; no failure is registered after accelerated fatigue tests, equivalent of 12-year cycles.	[177]
mNG composite hydrogels	Covalent conjugation of mNCC on Me-Gel backbone via NHS/EDC crosslinking	Encapsulated HADMSCs on mNG displayed phenotypic properties found within the heart valve spongiosa; lower expression of osteogenic genes indicates resistance toward calcification.	[178]
BC/PVA anisotropic nanocomposites	Physical crosslinking by freeze-thaw cycles (20 °C/−20 °C); molding technique	Mechanical properties are similar to valve leaflet tissues, in both principal directions; the composition and number of freeze-thaw cycles substantially influence the tissue properties.	[179,180]
	Thermal processing; molding technique	Trileaflet mechanical heart valve mimics the non-linear mechanical properties and anisotropic behavior of the porcine heart valves.	[181,182]
Alginate-Based Scaffolds
PEG-DA/Alg hydrogels	Simultaneous 3D printing/photocrosslink ingmethods	The scaffolds with 10% Alg allow PAVICs to grow along the conduits surface, but less on the root and leaflet interstitium; high cell viability: 91.3 ± 10.7% (day 1) and 100% (day 7 and 21).	[137]
Alg/GEL hydrogels	3D bioprinting with mold extrusion technique	Printing accuracy: 84.3 ± 10.9%; Cell viability (7 days): 81.4 ± 3.4% (SMCs); 83.2 ± 4.0% (VICs); SMCs express α-SMA in stiff matrix; VICs express VIM in soft matrix.	[133]
Dop-Alg hydrogel coatings	Covalent bonding of Dop to Alg (EDC/NHS route); Crosslinking with GA	In vitro: only Dop-Alg determines a decrease in the Ca content: 2.919 ± 0.252 mg/L—day 3; 0.725 ± 0.012 mg/L—day 6; In vivo: the largest decrease in Ca content for Dop-Alg: 1.737 ± 0.124 mg/L—day 20; 0.675 ± 0.084 mg/L—day 30.	[183]

Abbreviations: A&R—aligned and random; ACAN—aggrecan; Alg—alginate; AP—adhesive proteins; BC—bacterial cellulose; bFGF—basic fibroblast growth factor; BP—bovine pericardium; CD34—mouse antibody; Ca—calcium; CA—cellulose acetate; CH—chitosan; CNF—cellulose nanofibrils; COL IV—collagen type IV; CTA—cetyltrimethylammonium bromide; DBP—decellularized bovine pericardium; Dop—dopamine; DPAV—decellularized porcine aortic valve; EC—endothelial cells; EDC—1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide; EOA—effective orifice area; EPC—endothelial progenitor cells; FI—fibroblast; Gel—gelatin; GA—glutaraldehyde; HADMSCs—Human adipose-derived mesenchymal stem cells; HEP—heparin; IPNs—interpenetrated networks; Me-GEL—methacrylated gelatin; Me-HA—methacrylated HA; mNG—mNCC—TEMPO-modified nanocrystalline cellulose; MOHA—methacrylated oxidized HA; MSCs—mesenchymal stem cells; MVICs—mitral valve interstitial cells; NHS—N-hydroxysuccinimide; OCAs—ovine carotid arteries cells; P4HB—poly-4-hydroxybutyrate; PAVICs—porcine aorta valve interstitial cells; PCL—polycaprolactone; PEG-DA—poly(ethylene glycol) diacrylate; PGS-PCL—poly(glycerol sebacate)-polycaprolactone; PHA—polyhydroxyalkanoates; PHVs—polymeric heart valves; PI—pinwheeling index; PP—polypropylene; PU—polyurethane; PVA—poly(vinyl alcohol); RF—regurgitant fraction; RGD—Arginine-Glycine-Aspartate peptides; RSS—Reynolds Shear Stress; SilylHA—silylated HA; α-SMA—α-smooth muscle actin; SMCs—smooth muscle cells; TCPS—tissue culture polystyrene; VICs—valvular interstitial cells; VIM—vimentin; YIGSRG—tyrosine-isoleucine-glycine-serine-arginine-glycine malinins.