From waste of marine culture to natural patch in cardiac tissue engineering

Abstract

Sea squirt, as a highly invasive species and main biofouling source in marine aquaculture, has seriously threatened the biodiversity and aquaculture economy. On the other hand, a conductive biomaterial with excellent biocompatibility, and appropriate mechanical property from renewable resources is urgently required for tissue engineering patches. To meet these targets, we presented a novel and robust strategy for sustainable development aiming at the marine pollution via recycling and upgrading the waste biomass-sea squirts and serving as a renewable resource for functional bio-scaffold patch in tissue engineering. We firstly demonstrated that the tunic cellulose derived natural self-conductive scaffolds successfully served as functional cardiac patches, which significantly promote the maturation and spontaneous contraction of cardiomyocytes both in vitro and enhance cardiac function of MI rats in vivo. We believe this novel, feasible and "Trash to Treasure" strategy to gain cardiac patches via recycling the waste biomass must be promising and beneficial for marine environmental bio-pollution issue and sustainable development considering the large-scale consumption potential for tissue engineering and other applications.

Keywords: Biofouling; Cardiac tissue engineering; Cellulose; Myocardial infarction; Sea squirts.

Graphical abstract

Fig. 1

The sea squirts-derived cardiac patch for myocardial infarction from waste of marine culture. The sea squirts, the waste of marine culture, could form the conductivity and well-aligned hydrogel after treating with acid and alike and significantly enhance the cardiac function of myocardial infarction rats.

Fig. 2

The preparation of tunic cellulose hydrogel. (a) The preparation procedure of pristine tunic, tunic hydrogel and PTC hydrogel. (b) The elemental analysis of pristine tunic, tunic hydrogel and PTC hydrogel. (c) XRD analysis for pristine tunic, tunic hydrogel and PTC hydrogel. (d) FTIR spectra of pristine tunic, tunic hydrogel and PTC hydrogel. TGA (e) and DTG (f) curves of pristine tunic, tunic hydrogel and PTC hydrogel.

Fig. 3

The morphological, conductive and mechanical characteristics of the scaffold. The SEM images of pristine tunic (a1), tunic hydrogel (a2) and PTC hydrogel (a3), scale bars: 200 nm. The inset are corresponding photos of contact angle on the surface of samples. (a4) The uptake water analysis of pristine tunic, tunic hydrogel and PTC hydrogel n = 4. (b1-3) Surface morphology and (b4) corresponding surface roughness Rq of pristine tunic (b1), tunic hydrogel (b2) and PTC hydrogel (b3) revealed by AFM test. The current distribution of pristine tunic (c1), tunic hydrogel (c2) and PTC hydrogel (c3) revealed by e-AFM test, n = 4. (c4) Statistical analysis of conductivity in pristine tunic, tunic hydrogel and PTC hydrogel n = 4. (d) The stress-strain curves of pristine tunic, tunic hydrogel and PTC hydrogel. (e) The Young's modulus of pristine tunic, tunic hydrogel and PTC hydrogel n = 3. (f) The degradation ratio of pristine tunic, tunic hydrogel and PTC hydrogel in physiological environment n = 4. All data are presented as mean ± SD. *P < 0.05, **P < 0.01.

Fig. 4

The morphological and functional characteristics of cardiomyocytes in scaffolds. (a) The morphology and maturation analysis of CMs in different scaffolds at day 7 of culture. The SEM of CMs seeded on pristine tunic, tunic hydrogel and PTC hydrogel, scale bars: 50 μm. The F-actin stained of cytoskeleton of CMs on pristine tunic, tunic hydrogel and PTC hydrogel. Expression of cardiac-specific proteins of α-actinin (green) and CX-43 (red) in the CMs on pristine tunic, tunic hydrogel and PTC hydrogel. Scale bars: 20 μm. (b) Western blotting detection for the expressions of α-actinin protein and CX-43 protein in CMs in different scaffolds at day 7 of culture. (c–d) The quantitative proteins expression of CX-43 (c) and α-actinin (d) in CMs in different scaffolds based on western blotting detection, n = 4. (e–g) Calcium transient of CMs on different scaffolds at day 7 of culture. (h) The analysis of spontaneous contraction activity of CMs seeded on pristine tunic, tunic hydrogel and PTC hydrogel culture of day 7. All data are presented as mean ± SD. *P < 0.05, **P < 0.01. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Fig. 5

Repair effect of patch in myocardial infarction rats. (a) The echocardiographic images of pretransplant (above) and posttransplant (bottom) in the sham group (control group), the MI group, tunic hydrogel and PTC hydrogel group. (b–e) Representative parameters of left ventricular function based on echocardiography of different groups after 4 weeks of implantation. (f) Masson's staining displayed the fibrous tissue (blue) and myocardium (red) of sections of hearts from animals in different groups. Scale bars: 1 mm. Statistical analysis of infarct size and infarct wall thickness of the infarcted heart in different group (bottom), n = 3. (g) vWF immunostaining (red) and α-SMA immunostaining (green) within infarcted area in different groups, n = 4. Scale bars: 50 μm. The different microvessel densities within infarcted region in different groups based on vWF/α-SMA immunostaining staining. All data are presented as mean ± SD. *P < 0.05, **P < 0.01. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)