Pectin is a complex, branched and acidic polysaccharide polymer consisting a core of alternating α-(1-4)-linked D-galacturonic acid and α-(1,2)-L-rhamnose units. Recently, pectin has been investigated for its use in various biomedical applications such as food use, drug delivery, cosmetics, and scaffolding for cells. In this study, pectin was isolated from cyanobacterium Spirulina maxima (SmP), and its immunomodulatory, wound healing and regeneration were assessed using zebrafish (Danio rario) model. Upon the zebrafish larvae exposure with SmP (25 and 50 µg/mL) and SmP (4%) supplemented zebrafish were resistant to both Edwardsiella piscicida and Aeromonas hydrophila infections. Transcriptional profile described that the SmP exposed larvae, up-regulated the antimicrobial enzyme (lysozyme), mucin (muc5.1, muc5.2, and muc5.3), and anti-oxidants (catalase and superoxide dismutase). SmP fed zebrafish gut showed >2-fold induced pro-inflammatory cytokine (il1β) and chemokines (cxcl18b, ccl34a.4 and ccl34b.4).
The wound healing function of SmP was investigated by in-vitro using the human dermal fibroblast cells (HDFs). SmP exposed (12.5 and 25 µg/mL) HDFs were significantly (p<.001) reduced the open wound area% as 32 and 12 %, respectively compared to control group (44%) at 18 hpe. Furthermore, zebrafish adult was also displayed significantly higher (p<.05) WHP upon the tropical application of SmP (46%) than the control (38%). Expression of wound healing related genes such as tgfβ1, timp2b, mmp9, tnfα, il-1β, and chemokines (cxcl18b, ccl34a.4 and ccl34b.4) were up-regulated in both muscle and kidney tissues suggesting SmP is a modulator of wound healing activity in zebrafish.
The capacity of SmP on fin regeneration in larval zebrafish was assessed by exposing to SmP (25 and 50 µg/mL). Regenerated fin area was significantly (p<.001) increased upon SmP exposure (50 µg/mL) at 2 and 3 dpa). Collectively, these results demonstrate that marine pectin derived from S. maxima displays multifunctional modulatory role in immune response, wound healing and regeneration hence, SmP could be applied for broad range of biomedical applications.