Table 1 Main elements influencing PU grafts in cardiovascular diseases

Physicomechanical features

- Elasticity depends on the usage, having proper modulus (without being too stiff). For cardiac tissue, proper range tensile strength is 3–15 kPa, modulus 10–50 kPa, and strain of 22–90%

Young, s modulus (MPa)

1.91 ± 0.49

1.19 ± 0.31

4.57–7.29

[46,47,48,49,50,51,52,53]

Max tensile strength (σf, MPa)

9.48 ± 1.27

1.61 ± 0.37

60.45 ± 8.01

Ultimate strain (εf) (%)

521 ± 23

166 ± 27.6

512.32

T_g (°C)

−34

–

−41.70- −44.91

Tm (°C)

47.8

–

63.5–60.9

MW g/mol)

35,867

1000–3500

42,500–5000

Degradation

- Polyester Pus: (hydrolytically unstable)

- Polyether-based Pus (relatively insensitive to hydrolysis but susceptible to oxidative degradation)

- Polyether-based PUs showed more stability than PCU and polyester-based PUs

- If cell growth is restricted by slow degraded PUs, combining with fast-degraded polymer is the solution

- The presence of antioxidants could inhibit the oxidative biodegradation

[34, 47, 54,55,56]

Porosity

- Porosity must allow cell/tissue infiltration

- not promote degradation

- support cell attachment and growth

[57, 58]

Blood- compatibility

- Blood-contacting PUs such as vascular scaffolds decreasing of platelet and white blood cell activation is required.

[58, 59]