Pleural tissue repair with cord blood platelet gel

Abstract

Background: Prolonged air leak is the major cause of morbidity after pulmonary resection. In this study we used in vitro and in vivo experiments to investigate an innovative approach based on the use of human umbilical cord blood platelet gel.

Materials and methods: In vitro, a scratch assay was performed to test the tissue repair capability mediated by cord blood platelet gel compared to the standard culture conditions using human primary mesothelial cells. In vivo, an iatrogenic injury was made to the left lung of 54 Wistar rats. Cord blood platelet gel was placed on the injured area only in treated animals and at different times histological changes and the presence of pleural adhesions were evaluated. In addition, changes in the pattern of soluble inflammatory factors were investigated using a multiplex proteome array.

Results: In vitro, mesothelial cell damage was repaired in a shorter time by cord blood platelet gel than in the control condition (24 versus 35 hours, respectively). In vivo, formation of new mesothelial tissue and complete tissue recovery were observed at 45±1 and 75±1 hours in treated animals and at 130±2.5 and 160±6 hours in controls, respectively. Pleural adhesions were evident in 43% of treated animals compared to 17% of controls. No complications were observed. Interestingly, some crucial soluble factors involved in inflammation were significantly reduced in treated animals.

Discussion: Cord blood platelet gel accelerates the repair of pleural damage and stimulates the development of pleural adhesions. Both properties could be particularly useful in the management of prolonged air leak, and to reduce inflammation.

Figures

Figure 1

The effects of FBS and CB platelet releasate on mesothelial repair in a scratch assay. (A) Reconstitution of mesothelial lining in the presence of FBS (standard condition, n =5) at T0, T8, T16, T24, T35; (B) Reconstitution of mesothelial lining in the presence of CB platelet releasate (n =5) at T0, T8, T16, T24; (C) Data are represented as mean ± SD. The P value was obtained performing an unpaired t-test. *P <0.0001.

Figure 2

TNF-α, IFN-γ and IL-2 concentrations in rat sera at 75 hours after pleural damage (control group, CG) and after CBPG treatment (treatment group, TG). Inflammatory factors were measured by proteome assay (pg/mL; CG n =4, TG n =6; median and range). The P value was obtained performing an unpaired t-test. *P <0.0001; **P <0.0003.

Figure 3

Presence of a pleural adhesion on the thoracotomy.

Figure 4

Histological sections of rat lung in the two different groups. On the left side the treated animals: (A) recent subpleural damage characterised by marked haemorrhagic extravasation, fibrin-rich clot bleeding associated with acute and chronic inflammation and fibroblast hyperplasia; (B) subpleural damage with a visible new mesothelial lining; (C) subpleural damage no longer visible. Complete mesothelial repair; (D) late subpleural damage in presence of weakly basophilic material due to Alcian blue 8GX staining. On the right side the controls: (E) recent subpleural damage characterised by marked haemorrhagic extravasation, fibrin-rich clot bleeding associated with acute inflammation; (F) subpleural damage with leucocyte-fibrin clot associated with scattered scar-like components; (G) subpleural damage in an advanced stage of mesothelial tissue repair; (H) subpleural damage no longer visible. Complete mesothelial repair.

Figure 5

Representative trends of tissue damage and repair in treated and control animals over time (hours): (A) surgical injury, (B) strongly damaged, (C) still evident damage, (D, bold grey line) initial lining, (E) evident lining, (F, bold grey line) complete tissue repair.