Table 6 Performance of composites, blends and hybrid materials based on natural polymers for ligament/tendon TE

Silk-Col

Col -sponge incorporated into a freeze-dried knitted silk mesh

(i) addition of: rhSDF-1 alpha

(ii) no rhSDF-1 alpha^a

Ligament

In vivo, rabbit model

ND

7.02 ± 1.25 (at 16 weeks after surgery)

ND

Fibroblasts distribution throughout the scaffold, at 4 weeks post-implantation

At 16 weeks postoperatively, host cells had invaded the core of the scaffold

[102]

49.49 ± 10.14 (at 16 weeks post surgery)

ND

~ 25 ± 12

At 2 weeks post-reconstruction, spindle tendon-like cells and vascularization

At 12 weeks, ligament-ECM deposition

[101]

Ligament/tendon

In vitro (BMSCs); In vivo, rabbit model

ND

24.3 ± 2.9

ND

47.0 ± 7.4

At 15–360 days after implantation, tissue ingrowth by fibroblasts between the fibers

At 4 weeks, denser ECM, larger number of cells, spindle-shaped morphology

Rarely vascularity; no evident inflammation

[54]

In vitro (human embryonic-stem cells MSCs)

In vivo, mouse model

(i) Dynamic mechanical stress

(ii) No mechanical stress

24.44 ± 10.03 (unseeded)

ND

In vitro: MSCs adhesion, proliferation

(i) After 14 days, cells elongation, aligned along the direction of mechanical stress

In vivo: (i) Aligned cells and larger collagen fibers comparing to (ii) After 4 weeks post-surgery, tendon-related ECM, indicating tenocyte-lineage

[98]

Tendon

In vitro (BMSCs, HDF), Achilles tendon fibroblasts (ATFs)

In vivo, rat model^a

(i) 45.3 ± 10.4

(ii) 32.6 ± 3.9^a

ND

(i) 68.5 ± 18.0 (ii) 65.7 ± 10.3^a

(i), (ii) At 4 days post-surgery neo-tendons appeared with cord-like shape^a

(i) Migratory BMSCs/HDF; vascularization; at 1 week post-surgery more fibroblasts and ECM; At 4 weeks, organized bundles of collagen fibers

[99]

CHI-HA

Braid with wetspun fibers

Ligament/Tendon

In vitro (fibroblast rabbit PT)

(i) static

(ii) stretch

(iii) rotation

(iv) stretch+ rotation

ND

Cell adhesion and proliferation

(iv) Higher cell proliferation after 21 days of culture and ECM production after 14 days of culture, comparing to i-(iii)

(iii) Higher cell proliferation than (i) and (ii)

[117]

Silk coated with Col-HA

(i) Knitted silk

(ii) Freeze-dried silk coated with Col-HA

Ligament

In vitro (Human ACL fibroblasts); In vivo, dog model

ND

In vitro: (ii) Higher cell attachment, proliferation and ECM synthesis than (i)

In vivo: (i), (ii) Synovitis; (ii) induced angiogenesis, new collagen formation and higher vascularity than (i)

[103]