Mechanical and biological properties of poly-ε-caprolactone membrane for pleurodesis: A preclinical study in pigs.

BACKGROUND/PURPOSE: Biomaterial implants are emerging as a treatment choice for pleurodesis; however, the optimal biomaterial and form for managing spontaneous pneumothorax, particularly post-video-assisted thoracic surgery, remain under investigation. This study evaluated the mechanical and biological properties of the poly-ε-caprolactone (PCL) membrane as a sclerosing agent for pleurodesis in Landrace pigs. METHODS: Twenty-four Landrace pigs were split into two groups for mechanical abrasion and PCL membrane pleurodesis, with the latter group's PCL meshes inserted using video-assisted thoracic surgery. The mechanical and biological properties of the PCL membrane were assessed in pigs at three, six, and 12 months after the procedure. This assessment involved a range of techniques, such as the T-Peel test, macroscopic evaluation with a scoring scale, microscopic examination, and biomechanical and molecular weight analysis. RESULTS: The PCL membrane group outperformed the traditional abrasion group, with stronger adhesions seen over longer implantation durations. This group also showed superior and more consistent results in both macroscopic and microscopic evaluations compared to the control group. The membrane-based method was easier and faster to perform than the control group's method, and importantly, no mortality occurred following membrane implantation. CONCLUSION: This study is the pioneering effort to present long-term findings regarding the mechanical and biological properties of the PCL membrane in an in vivo animal model. The membrane demonstrated better adhesion ability than that of traditional abrasion and showed reassuring biocompatibility in both the pig model, suggesting its potential as treatment for patients with primary spontaneous pneumothorax. Further clinical studies are needed to support these observations.

Study of poly-ɛ-caprolactone membranes for pleurodesis.

BACKGROUND/PURPOSE: Pleurodesis with biomaterial membrane is an emerging treatment method for pneumothorax. However, the ideal one for the common disease is still under debate. METHODS: We investigate the Poly-ε-caprolactone (PCL) membrane pleurodesis by using New Zealand White rabbits, which was sacrificed for examination one month later. Moreover, inflammation and fibrosis scoring were done under microscopic evaluation, as well as Western blot analysis in vitro and in vivo. RESULTS: Gross evaluation of pleurodesis score revealed that dense PCL membrane produced moderate pleural adhesion, while porous PCL membrane exhibited significantly higher pleurodesis scores. CONCLUSION: PCL membrane induced significant degree of adhesion, both within the abdomen and chest of the rabbits. The porous PCL membrane produces more intensive adhesion than dense one. Fibronectin plays an important role in the process of pleurodesis. Further study is required for the clinical application of the promising material.

Vicryl Mesh Coverage Reduced Recurrence After Bullectomy for Primary Spontaneous Pneumothorax.

BACKGROUND: Although thoracoscopic stapled bullectomy is a standard procedure for primary spontaneous pneumothorax (PSP), the postoperative recurrence rate is high. We investigated whether using a Vicryl (Ethicon, Somerville, NJ) mesh to cover the staple line after bullectomy reduces the postoperative recurrence rate. METHODS: Our single-blind, parallel-group, prospective, randomized controlled trial at 2 medical centers in Taiwan studied patients with PSP who were aged 15 to 50 years and required thoracoscopic bullectomy. On the day of operation, patients were randomly assigned (1:1) to receive Vicryl mesh (mesh group) or not (control group) after thoracoscopic bullectomy with linear stapling and mechanical apical pleural abrasion. Randomization was achieved using computer-generated random numbers in sealed envelopes. Our primary end point was the pneumothorax recurrence rate within 1 year after the operation (clinicaltrials.gov number, NCT01848860.) RESULTS: Between June 2013 and March 2016, 102 patients were assigned to the mesh group and 102 to the control group. Within 1 year after operation, recurrent pneumothorax was diagnosed in 3 patients (2.9%) in the mesh group compared with 16 (15.7%) in the control group (P = .005). The short-term postoperative results and hospitalization duration were comparable between the groups. CONCLUSIONS: For thoracoscopic bullectomy with linear stapling and mechanical apical pleural abrasion, the use of a Vicryl mesh to cover the staple line is effective for reducing the postoperative recurrence of pneumothorax. Vicryl mesh coverage can be considered an optimal adjunct to the standard surgical procedure for PSP.

Hyaluronic acid on the urokinase sustained release with a hydrogel system composed of poloxamer 407: HA/P407 hydrogel system for drug delivery.

Pleural empyema is an inflammatory condition characterized by accumulation of pus inside the pleural cavity, which is usually followed by bacterial pneumonia. During the disease process, the pro-inflammatory and pro-fibrotic cytokines in the purulent pleural effusion cause proliferation of fibroblasts and deposition of extracellular matrix, which lead to fibrin deposition and fibrothorax. Urokinase instillation therapy through a chest drainage tube is frequently used for fibrinolysis in patients with empyema. However, urokinase treatment requires multiple instillation (2-3 times per day, for 4-8 days) and easily flows out from the chest drainage tube due to its high water solubility. In this in vitro study, we developed a thermo-responsive hydrogel based on poloxamer 407 (P407) combined with hyaluronic acid (HA) for optimal loading and release of urokinase. Our results show that the addition of HA to poloxamer gels provides a significantly more compact microstructure, with smaller pore sizes (**p < 0.001). The differential scanning calorimetry (DSC) profile revealed no influence on the micellization intensity of poloxamer gel by HA. The 25% poloxamer-based gel was significantly superior to the 23% poloxamer-based gel, with slower gel erosion when comparing the 16th hour residual gel weight of both gels (*p < 0.05; **p < 0.001). The 25% poloxamer-HA gel also exhibited a superior urokinase release profile and longer release time. A Fourier-transform infrared spectroscopy (FT-IR) study of the P407/HA hydrogel showed no chemical interactions between P407 and HA in the hydrogel system. The thermoresponsive P407/HA hydrogel may have a promising potential in the loading and delivery of hydrophilic drugs. On top of that, in vitro toxicity test of this combination demonstrates a lower toxicity.

Evaluation of pleurodesis by poly-ε-caprolactone (PCL) gel in an animal model using New Zealand white rabbits.

BACKGROUND/PURPOSE: Pleurodesis with biomaterial implant is an emerging treatment method for pleural diseases. However, the ideal biomaterial or the optimal form for the common diseases is still under investigation. In our previous study, Poly-ε-caprolactone (PCL) membrane produces significant pleurodesis in New Zealand White rabbit animal models. METHODS: We investigate the Poly-ε-caprolactone (PCL) gel pleurodesis by animal models using New Zealand White rabbits, which were sacrificed for examination after one month. Thirty-Six New Zealand White rabbits were randomized into three groups equally to undergo procedures. Gross pleurodesis scoring was evaluated. Additionally, inflammation and fibrosis scoring were done under microscopic evaluation, as well as Western blot analysis. RESULTS: Gross evaluation of pleurodesis score revealed that lower concentrated PCL gel (10%) produced moderate pleural adhesion, while higher concentrated PCL gel (25%) showed significantly higher pleurodesis scores. (P < 0.05) Control group with thoracostomy alone produced almost no pleurodesis (P < 0.05). Western blot showed fibronectin expression was more evident in the 25% PCL gel than 10% one. CONCLUSION: PCL gel induced significant degree of pleurodesis in the rabbits. The 25% PCL gel produces more intensive adhesion than 10% one. Fibronectin plays an important role in the process of pleurodesis. Further study is required for the clinical application of the promising biomaterial with gel form.

A theranostic micelleplex co-delivering SN-38 and VEGF siRNA for colorectal cancer therapy.

The development of an efficient colorectal cancer therapy is currently a public health priority. In the present work, we proposed a multifunctional theranostic micellar drug delivery system utilizing cationic PDMA-block-poly(ε-caprolactone) (PDMA-b-PCL) micelles as nanocarriers of SN-38 (7-ethyl-10-hydroxycamptothecin), ultra-small superparamagnetic iron oxide nanoparticles (USPIO), and small interfering RNA (siRNA) that targets human vascular endothelial growth factor (VEGF). The VEGF siRNA was conjugated to polyethylene glycol (PEG) (siRNA-PEG) before complexation with the micelles in order to improve the siRNA's stability and to prolong its retention time in the blood circulation. To further improve the in vivo biosafety, we prepared mixed micelles using mPEG-PCL together with PDMA-b-PCL copolymer. The SN-38/USPIO-loaded siRNA-PEG mixed micelleplexes passively targeted to tumor regions and synergistically facilitated VEGF silencing and chemotherapy, thus efficiently suppressing tumor growth via a multi-dose therapy regimen. Additionally, the SN-38/USPIO-loaded siRNA-PEG mixed micelleplexes acted as a negative magnetic resonance imaging (MRI) contrast agent in T2-weighted imaging, resulting in a powerful tool for the diagnosis and for tracking of the therapeutic outcomes. In summary, we established a theranostic micellar drug and gene delivery system that not only synergistically combined gene silencing and chemotherapy but also served as a negative MRI contrast agent, which reveal its potential as a novel colorectal cancer therapy.