Table 4 Performance of synthetic biodegradable polymers in ligament/tendon TE

PLGA

(i) Electrospun PLGA fibers onto knitted PLGA

(ii) Knitted PLGA scaffold

Ligament/tendon

In vitro (porcine BMSCs)

(i) 0.85 ± 0.2

(ii) 0.64 ± 0.2 (at 14 days of culture)

ND

(i) Higher BMSCs attachment, proliferation, ECM deposition compared to (ii)

[71]

Electrospun Aligned

(i) Nanofiber

diameter (320,680 nm)

(ii) Microfiber diameter (1.8 µm)

In vitro (Human rotator cuff fibroblast)

(i) 421 ± 23

(ii) 510 ± 32

(for 1.8 µm)

ND

(i) ~ 13

(ii) ~ 14

(for 1.8 µm)

ND

(i) Higher cells proliferation

(ii) Higher tendon-related ECM markers, after 14 days of culture

[87]

Electrospun

(i) Aligned nanofibers

(ii) Random nanofibers

Tendon

In vitro (Human rotator cuff fibroblast)

(i) 341 ± 30

(ii) 107 ± 23

ND

(i) 12.0 ± 1.5

(ii) 3.7 ± 0.2

ND

Cellular adhesion, proliferation

(i) Elongated morphology and orientation along the fibers

(ii) Polygonal shape, random orientation

[70]

(i) Rectangular braid

(ii) Circular braid (scaffold with 3 regions)

Ligament

In vitro (fibroblasts: rabbit ACL; mouse BALB/C)

ND

(i) 217 ± 11

(ii) 212 ± 25

(i) 705 ± 36

(ii) 907 ± 132

Cellular adhesion and proliferation

(i) ACL and BALB/C spread along the fibers

(ii) Only ACL proliferate along the fibers

[6]

PLLA

Rectangular braid (scaffold with 3 regions)

Ligament/tendon

In vitro (rabbit ACL; MCL;AT; PT fibroblast)

ND

Cellular adhesion, proliferation, elongation along the fibers

ACL with higher matrix production

[11, 74]

Braided scaffolds of (i) 3, (ii) 4; (iii) 5 aligned electrospun nanofibers

In vitro (human MSCs)

(i) 55.0 ± 2.8

(ii) 47.8 ± 7.5

(iii) 47.6 ± 2.8

ND

(i) 7.62 ± 0.2

(ii) 6.57 ± 0.5

(iii) 6.67 ± 0.4

ND

(i) hMSCs adhesion and proliferation, orientation along the fibers; Expression of pluripotency genes

(ii), (iii) ND

[88]

(i) Braided scaffold

(ii) Twisted fiber scaffold

(iii) Braid-twist scaffold

Ligament

In vitro (rabbit PT fibroblasts)

(i) 810.2 ± 233.5

(ii) 888.2 ± 60.7; (iii) 428.2 ± 60.7

ND

(i) ~ 52.3 ± 7.7

(ii) 80.9 ± 6.9

(iii) 81.6 ± 1.6

ND

(i), (iii) Comparable cellular adhesion, proliferation. Production of ECM, after 7 days of culture

(ii) ND

[75, 89]

5 × 5 Square braid:

(i) Scaffold before implantation

(ii) Seeded

(iii) Unseeded

(i), (ii) 4 weeks post-surgery)

In vivo (after seeded with primary rabbit ACL cells) rabbit model

(i) 354.4 ± 68.5

(ii) 108.4 ± 27.7

(iii) 103.0 ± 53.9

ND

(i) 332.2 ± 19.6

(ii) 239.0 ± 43

(iii) 209.0 ± 73.5

(i) ND

(ii) After 12 weeks, vascularization and greater tissue ingrowth and alignment of collagen fibers compared to (iii) A mild inflammatory response was observed in (i) and (ii)

[76]

Electrospun

(i) Aligned

(ii) Random nanofibers

Tendon

In vitro/in vivo, (human tendon stem cells (hTSCs))

mouse model

(i) 22.76 ± 5.63

(ii) 0.63 ± 0.56

ND

hTSCs adhesion, proliferation

In vitro/in vivo (i) cells with spindle-shaped and well orientated; teno-lineage differentiation

(ii) Cells with round shapes; random distribution

[90]

(i) PLLA

(ii) PLGA

(iii) PGA

(iv) Fn pre-coated: (i)–(iii)

Circular braid (multi-filament yarns-3 regions)

Ligament

In vitro (rabbit ACL fibroblasts)

ND

(i) 165 ± 33

(ii) 117 ± 12

(iii) 378 ± 18

(iv) ND

(i) 298 ± 59

(ii) 215 ± 23;

(iii) 502 ± 24

(iv) ND

ACL adhesion, proliferation

(i) Cells with spindle-like morphology

(ii) Cells with a form of spiked rods

(iii) Cells form large globular aggregates

(iv) Higher ECM production; Fn improved cellular proliferation mainly on i)

[72]

PCLF

UV-crosslinked PCLF solution injected over

3D printed mold-square porous: (i) 500 × 500 µm

(ii) 750 × 750 µm (mold designed by SolidWorks CAD software)

Ligament

In vitro (AMSCs)

ND

(i), (ii) AMSCs adhesion and proliferation, filling the pores, after 14 days of culture

Expression of ligament-ECM in the presence of growth factors

[86]

PCL

Twisted electrospun fibers

(i) Under static conditions

(ii) Dynamic Loading

Tendon

In vitro (human MSCs)

(i) ~ 34 ± 6.8

(ii) ~ 27 ± 6.8 (acellular, after 21 days)

ND

(i) ~ 13 ± 0.7

(ii) ~ 12 ± 1.4 (acellular, after 21 days)

ND

Cellular adhesion/proliferation

Elongated cells along the fiber direction

(ii) Textured/round cells; Higher cell proliferation, comparing to (i)

(i) Cells flatter and fused together

(ii) Up-regulation of tendon genes, after 21 days

[91]