Fig. 6. Ex vivo and in vivo test to evaluate the sealing capability of the MeTro sealant using a porcine lung incision model.

(A) Ex vivo porcine lung burst pressure testing. (i) Image from the superficial wound created in deflated lung before sealing, (ii) wound covered with the MeTro sealant, (iii) representative graph depicting the incremental increase in pressure during ventilation, and (iv) average burst pressures for MeTro (n = 5), Evicel (n = 3), Progel (n = 5), and a suture control (n = 3). MeTro shows the highest burst pressure. (B) In vivo sealing capacity of MeTro using a porcine lung incision model (n = 3). (i and ii) A right lung lobe is exposed through a small lateral thoracotomy, and a standardized defect is created [broken line in (B, i)] and sealed by applying and photocrosslinking the MeTro (20% MeTro concentration with high methacryloyl substitution) sealant [broken line in (B, ii)]. (iii and iv) At postoperative days 7 and 14, freedom from pneumothorax was confirmed by sonography, as displayed in a representative ultrasound image at day 14, indicating the absence of any relevant amount of air in the intercostal space. (v) Representative histological sections of the lung leakage site after 14 days revealed sufficient formation of wound healing tissue [asterisks in (v); H&E staining] including a stable collagenous (blue) defect cover [asterisks in (vi); Masson’s trichrome staining]. (vii) H&E staining of the attachment of MeTro sealant to noninjured lung tissue around the defect site. (viii) Immunohistological staining of the defect area and the formed wound healing tissue (asterisks) did not show relevant macrophage (Mac2) or lymphocyte (CD3) infiltration. Scale bars, 200 μm (v to vii) and 100 μm (viii). Data are means ± SD (*P < 0.05 and **P < 0.01).