Bio-artificial pleura using autologous dermal fibroblast sheets to mitigate air leaks during thoracoscopic lung resection

Isogenic Transplantation of Hybrid Artificial Pleural Tissue Consisting of Rat Cells and Polyglycolic Acid Nanofiber Sheet Induces Restoration of Mesothelial Defects in Rat Model

BACKGROUND

Impairment of the visceral pleura following thoracic surgery often leads to air leaks and intrathoracic adhesions. For preventing such complications, mesothelial cell proliferation at the pleural defects can be effective. To develop new materials for pleural defects restoration, we constructed a hybrid artificial pleural tissue (H-APLT) combining polyglycolic acid (PGA) nanofiber sheets with a three-dimensional culture of mesothelial cells and fibroblasts and evaluated its therapeutic efficacy in a rat pleural defect model.

METHODS

After rat lungs were harvested, pleural mesothelial cells and lung fibroblasts were cultured separately. To construct H-APLT, the cells were then coated with multiple layers of fibronectin and gelatin, followed by a single layer of mesothelial cells on top of multiple layers of fibroblasts accumulated onto a collagen-coated PGA nanofiber sheet. Left lateral thoracotomy was performed, and H-APLTs were transplanted into a rat model with pleural defects (N = 8). After 2-12 weeks of transplantation, lung resection and histological analyses were performed.

RESULTS

H-APLTs exhibited a pleural structure with a highly integrated mesothelial layer in vitro. After transplantation, all eight rats survived until sacrifice. At 12 weeks post-transplantation, the mesothelial layer on the lung surface was observed to be without defects with no intrathoracic adhesions detected.

CONCLUSION

Successful isogenic engraftment of H-APLTs was achieved in a rat model of pleural defects. The combination of accumulated fibroblasts and collagen-coated PGA nanofiber sheets contributed to the maintenance of the mesothelial layer's structure and function, potentially preventing air leaks and intrathoracic adhesions.

Allogeneic fibroblast sheets prevent pulmonary air leaks caused by rat pleural defects without adhesion to the thoracic wall

Introduction

Pulmonary air leak (PAL) is one of a complication of thoracic surgery and an unavoidable problem after lung resection or pleural adhesion detachment. Conventional procedures to close PAL by applying polyglycolic acid (PGA) sheets are prone to pleural adhesion. This study evaluated the ability of allogeneic fibroblast sheet transplantation to prevent PALs.

Methods

Rat skin fibroblasts were prepared from transgenic rats expressing green fluorescent protein (GFP) and cultured on temperature-responsive culture dishes to harvest fibroblast sheets. Allogeneic fibroblast sheets or PGA sheets were transplanted onto the pleural defects of the left lung in F344/NJcl-rnu/rnu (athymic rat), Slc:SD (SD), and BN/SsNSlc (BN) rats to assess PAL and adhesion prevention. Histological and immunological analyses were conducted to evaluate lung tissue of PALs transplanted with fibroblast or PGA sheets.

Results

Fibroblast sheets and PGA sheets closed pleural defects with PALs in all rat models. Adhesions were observed in most rat models transplanted with PGA sheets, but no adhesions were observed in rat models transplanted with fibroblast sheets. Immunostaining for HBME-1 indicated the regeneration of pleura by fibroblast sheet transplantation on the defects without adhesions after 2 weeks and 3 months of transplantation.

Conclusions

Similar to autologous fibroblast sheet transplantation, the transplantation of allogeneic fibroblast sheets prevented PALs and closed pleural defects without adhesion between the visceral and parietal pleura. Therefore, it can be concluded that allogeneic fibroblast sheets can be used as a ready-to-use sealant for preventing postoperative PALs.

Dual-color FISH analyses of xenogeneic human fibroblast sheets transplanted to repair lung pleural defects in an immunocompromised rat model

BACKGROUND

Pulmonary air leaks (PALs) due to visceral pleura injury during surgery is frequently observed after pulmonary resections and the complication is difficult to avoid in thoracic surgery. The development of postoperative PALs is the most common cause of prolonged hospitalization. Previously, we reported that PALs sealants using autologous dermal fibroblast sheets (DFSs) harvested from temperature-responsive culture dishes successfully closed intraoperative PALs during lung resection.

OBJECTIVE

In this study, we investigated the fate of human DFSs xenogenetically transplanted onto lung surfaces to seal PALs of immunocompromised rat. Dual-color FISH analyses of human fibroblast was employed to detect transplantation human cells on the lung surface.

RESULTS

One month after transplantation, FISH analyses revealed that transplanted human fibroblasts still composed a sheet-structure, and histology also showed that beneath the sheet's angiogenesis migrating into the sheets was observed from the recipient tissues. FISH analyses revealed that even at 3 months after transplantation, the transplanted human fibroblasts still remained in the sheet. Dual-color FISH analyses of the transplanted human fibroblasts were sparsely present as a result of the cells reaching the end of their lifespan, the cells producing extracellular matrix, and remained inside the cell sheet and did not invade the lungs of the host.

CONCLUSIONS

DFS-transplanted human fibroblasts showed that they are retained within cell sheets and do not invade the lungs of the host.

A first-in-human clinical study of laparoscopic autologous myoblast sheet transplantation to prevent delayed perforation after duodenal endoscopic mucosal dissection

BACKGROUND

The detection rate of superficial non-ampullary duodenal epithelial tumors (SNADETs) has recently been increasing. Large tumors may contain malignant lesions and early therapeutic intervention is recommended. Endoscopic mucosal dissection (ESD) is considered a feasible treatment modality, however, the anatomical and physiological characteristics of the duodenum create a risk of postoperative perforation after ESD.

METHODS

To explore whether myoblast sheet transplantation could prevent delayed perforation after ESD, a first-in-human (FIH) clinical trial of laparoscopic autologous myoblast sheet transplantation after duodenal ESD was launched. Autologous myoblast sheets fabricated from muscle tissue obtained seven weeks before ESD were transplanted laparoscopically onto the serous side of the ESD. The primary endpoints were the onset of peritonitis due to delayed perforation within three days after surgery and all adverse events during the follow-up period.

RESULTS

Three patients with SNADETs ≥ 20 mm in size underwent transplantation of a myoblast sheet onto the serous side of the duodenum after ESD. In case 1, The patient's postoperative course was uneventful. Endoscopy and abdominal computed tomography revealed no signs of delayed perforation. Despite incomplete mucosal closure in case 2, and multiple micro perforations during ESD in case 3, cell sheet transplantation could prevent the postoperative massive perforation after ESD, and endoscopy on day 49 after transplantation revealed no stenosis.

CONCLUSIONS

This clinical trial showed the safety, efficacy, and procedural operability of this novel regenerative medicine approach involving transplanting an autologous myoblast sheet laparoscopically onto the serosa after ESD in cases with a high risk of delayed perforation. This result indicates the potential application of cell sheet medicine in treating various abdominal organs and conditions with minimal invasiveness in the future.

TRIAL REGISTRATION

jRCT, jRCT2073210094. Registered November 8 2021, https://jrct.niph.go.jp/latest-detail/jRCT2073210094 .

Tailoring cell sheets for biomedical applications

Cell sheet technology has emerged as a novel scaffold-free approach for cell-based therapies in regenerative medicine. Techniques for harvesting cell sheets are essential to preserve the integrity of living cell sheets. This review provides an overview of fundamental technologies to fabricate cell sheets and recent advances in cell sheet-based tissue engineering. In addition to the commonly used temperature-responsive systems, we introduce alternative approaches, such as ROS-induced, magnetic-controlled, and light-induced cell sheet technologies. Moreover, we discuss the modification of the cell sheet to improve its function, including stacking, genetic modification, and vascularization. With the significant advances in cell sheet technology, cell sheets have been widely applied in various tissues and organs, including but not limited to the lung, cornea, cartilage, periodontium, heart, and liver. This review further describes both the preclinical and clinical applications of cell sheets. We believe that the progress in cell sheet technology would further propel its biomedical applications.

Effects of refined nursing interventions in the operating room on surgical-site wound infection in patients with lung cancer: A meta-analysis

In this study, a meta-analysis was conducted to assess the effect of refined nursing interventions in the operating room on the incidence of surgical-site wound infections in patients undergoing lung cancer surgery to provide an evidence base for the prevention and management of nosocomial infections. A computerised literature search was used to identify randomised controlled trials (RCTs) on the application of refined nursing interventions in the operating room in patients undergoing lung cancer surgery published in the PubMed, EMBASE, Cochrane Library, China National Knowledge Infrastructure (CNKI), VIP and Wanfang databases from their inception until July 2023. The literature screening, data extraction and quality assessment of the included studies were performed independently by two researchers. RevMan 5.4 software was used for the meta-analysis. Twenty-eight studies were included in the analysis, with a total of 2406 patients, including 1210 patients in the refined nursing intervention group and 1196 patients in the control group. The results of the meta-analysis showed that the refined nursing interventions in the operating room significantly reduced the incidence of surgical-site wound infections in patients undergoing lung cancer surgery, compared with the control group (1.82% vs. 6.52%, odds ratio: 0.30, 95% CI: 0.19-0.47, p < 0.001), and shortened the length of hospital stay (standardised mean difference: -1.51 days, 95% CI: -1.92 to -1.11 days, p < 0.001). Current evidence suggests that the application of refined nursing interventions in the operating room is effective at reducing the incidence of surgical-site wound infections and shortening the length of hospital stay in patients undergoing lung cancer surgery. However, owing to the small number and low quality of the studies, more high-quality RCTs with large sample sizes are needed to confirm these results.

Fabrication Strategies for Engineered Thin Membranous Tissues

Thin membranous tissues (TMTs) are anatomical structures consisting of multiple stratified cell layers, each less than 100 μm in thickness. While these tissues are small in scale, they play critical roles in normal tissue function and healing. Examples of TMTs include the tympanic membrane, cornea, periosteum, and epidermis. Damage to these structures can be caused by trauma or congenital disabilities, resulting in hearing loss, blindness, dysfunctional bone development, and impaired wound repair, respectively. While autologous and allogeneic tissue sources for these membranes exist, they are significantly limited by availability and patient complications. Tissue engineering has therefore become a popular strategy for TMT replacement. However, due to their complex microscale architecture, TMTs are often difficult to replicate in a biomimetic manner. The critical challenge in TMT fabrication is balancing fine resolution with the ability to mimic complex target tissue anatomy. This Review reports existing TMT fabrication strategies, their resolution and material capabilities, cell and tissue response, and the advantages and disadvantages of each technique.

Rapid and chronological expression of angiogenetic genes is a major mechanism involved in cell sheet transplantation in a rat gastric ulcer model

Introduction

Cell sheet technology has been applied in the treatment of patients with severe cardiac failure. Although the paracrine effect of cell sheets accelerating angiogenesis is thought to be the intrinsic mechanism for improvement of cardiac function, little is known about how a cell sheet would function in the abdomen.

Methods

We used acetic acid-induced gastric ulcer rat model to elucidate the mechanisms of myoblast sheet transplantation in the abdomen. Myoblast sheet was implanted onto the serosal side of the gastric ulcer and the effect of sheet transplantation was analyzed. The maximal diameter of the ulcer and the changes in the gene expression of various growth factors in transplanted site was analyzed. The progenitor marker CD34 was also examined by immunohistochemistry.

Results

Cell sheet transplantation accelerated the ulcer healing. qPCR showed that angiogenic growth factors were significantly upregulated around the ulcer in the transplantation group. In addition, at first, HIF-1a and SDF-1 continued to increase from 3 h after transplantation to 72 h, then VEGF increased significantly after 24 h with a slight delay. An immunohistochemical analysis showed a statistically significant increase in CD34 positivity in the tissue around the ulcer in the transplantation group.

Conclusion

Myoblast sheet secreted various growth factors and cytokines immediately after transplantation onto the serosal side of artificial ulcer in the abdomen. Autonomous secretion, resulting in the time-dependent and well-orchestrated gene expression of various growth factors, plays a crucial role in the cell sheet function. Cell sheet transplantation is expected to be useful to support angiogenesis of the ischemic area in the abdominal cavity.

Expansion of fibroblast cell sheets using a modified MEEK micrografting technique for wound healing applications

Cell sheet engineering, a scaffold-free approach to fabricate functional tissue constructs from several cell monolayers, has shown promise in tissue regeneration and wound healing. Unfortunately, these cell sheets are often too small to provide sufficient wound area coverage. In this study, we describe a process to enlarge cell sheets using MEEK micrografting, a technique extensively used to expand skin autografts for large burn treatments. Human dermal fibroblast cell sheets were placed on MEEK's prefolded gauze without any use of adhesive, cut along the premarked lines and stretched out at various expansion ratios (1:3, 1:6 and 1:9), resulting in regular distribution of many square islands of fibroblasts at a much larger surface area. The cellular processes essential for wound healing, including reattachment, proliferation, and migration, of the fibroblasts on expanded MEEK gauze were superior to those on nylon dressing which served as a control. The optimal expansion ratio with the highest migration rate was 1:6, possibly due to the activation of chemical signals caused by mechanical stretching and an effective intercellular communication distance. Therefore, the combination of cell sheet engineering with the MEEK micrografting technique could provide high quality cells with a large coverage area, which would be particularly beneficial in wound care applications.

Highly feasible procedure for laparoscopic transplantation of cell sheets under pneumoperitoneum in porcine model

INTRODUCTION

Cell sheet technology is one of the most successful methodologies in regenerative medicine. Various applications of cell sheets have been introduced in first-in-human studies in several clinical fields. When transplanting a cell sheet into internal organs, a relatively large incision is required for delivery due to difficulty handling the sheet. We developed a laparoscopic delivery procedure for safe and easy transplantation of cell sheets in a porcine model.

METHODS

Pneumoperitoneum was established by inflation with CO2. First, to increase the strength during handling, fibrin was sprayed onto the surface of the cell sheet, and then a myoblast sheet was placed onto the newly developed carrier. The sheets were pinched with laparoscopic forceps to insert into the abdominal cavity through the laparoscopic port. Myoblast sheets were then applied to the surface of the liver, colon, small intestine, and stomach, and procedure times were measured. At three days post transplantation, a histopathological examination was performed to confirm engraftment of the sheet. The function and engraftment were also analyzed in a duodenal endoscopic submucosal dissection (ESD) model.

RESULTS

The fibrin-processed myoblast sheet was able to be managed with conventional laparoscopic forceps without breaking. Despite the drastic change in air pressure by passing through the laparoscopic port, the sheets suffered no apparent damage. The transplantation procedure times did not markedly differ among transplant sites. A histopathological examination revealed thin-layered, desmin-positive cells at each transplant site. With transplantation following ESD, the engrafted myoblast sheets effectively prevented delayed perforation.

CONCLUSIONS

Our procedure is simple, and the system involves a carrier made of medically fit silicon, commercially available fibrin glue and conventional laparoscopic forceps. Our procedure is a powerful tool for laparoscopical cell sheet transplantation.

A novel alveolar epithelial cell sheet fabricated under feeder-free conditions for potential use in pulmonary regenerative therapy

Introduction

Methods

Results

Conclusions

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Alveolar epithelial cells were cultured and expanded under feeder-free conditions.

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Alveolar epithelial cell sheets were generated using temperature-responsive dishes.

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Alveolar epithelial cell sheets engrafted after transplantation onto rat lung.

•

The sheets retained alveolar epithelial cell characteristics after transplantation.

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These cell sheets potentially could be used for pulmonary regenerative therapy.

Cell sheet transplantation prevents inflammatory adhesions: A new treatment for adhesive otitis media

Introduction

We developed a new treatment method that combines tympanoplasty with transplantation of autologous cultured nasal mucosal epithelial cell sheets to regenerate the mucosa of patients with adhesive otitis media, which has been difficult to treat effectively. We verified whether this procedure could be performed safely and measured its therapeutic efficacy.

Methods

Autologous nasal mucosal epithelial cell sheets were manufactured at a good manufacturing practice-compliant cell processing facility using autologous nasal mucosal tissue. We performed tympanoplasty and transplanted the cell sheets into the middle ear cavity in six patients with adhesive otitis media.

Results

The manufactured autologous cultured epithelial cell sheets met the predetermined quality standards and were successfully transplanted safely in all cases. Computed tomography findings after cell sheet transplantation showed that aeration in the tympanic cavity was maintained or restored in five of the six patients (83.3%). Four of the six (66.7%) patients had postoperative air-bone gap within 20 dB, which is considered a postoperative success in tympanoplasty for chronic middle ear disease.

Conclusions

The results of this clinical study suggest that tympanoplasty with cell sheet transplantation can be used to treat adhesive otitis media by reliably preventing re-adhesion of the tympanic membrane.

Preparation of a Cage-Type Polyglycolic Acid/Collagen Nanofiber Blend with Improved Surface Wettability and Handling Properties for Potential Biomedical Applications

Electrospun biobased polymeric nanofiber blends are widely used as biomaterials for different applications, such as tissue engineering and cell adhesion; however, their surface wettability and handling require further improvements for their practical utilization in the assistance of surgical operations. Therefore, Polyglycolic acid (PGA) and collagen-based nanofibers with three different ratios (40:60, 50:50 and 60:40) were prepared using the electrospinning method, and their surface wettability was improved using ozonation and plasma (nitrogen) treatment. The effect on the wettability and the morphology of pristine and blended PGA and collagen nanofibers was assessed using the WCA test and SEM, respectively. It was observed that PGA/collagen with the ratio 60:40 was the optimal blend, which resulted in nanofibers with easy handling and bead-free morphology that could maintain their structural integrity even after the surface treatments, imparting hydrophilicity on the surface, which can be advantageous for cell adhesion applications. Additionally, a cage-type collector was used during the electrospinning process to provide better handling properties to (PGA/collagen 60:40) blend. The resultant nanofiber mat was then incorporated with activated poly (α,β-malic acid) to improve its surface hydrophilicity. The chemical composition of PGA/collagen 60:40 was assessed using FTIR spectroscopy, supported by Raman spectroscopy.

Thermoresponsive interfaces obtained using poly(N-isopropylacrylamide)-based copolymer for bioseparation and tissue engineering applications

Poly(N-isopropylacrylamide) (PNIPAAm) is the most well-known and widely used stimuli-responsive polymer in the biomedical field owing to its ability to undergo temperature-dependent hydration and dehydration with temperature variations, causing hydrophilic and hydrophobic alterations. This temperature-dependent property of PNIPAAm provides functionality to interfaces containing PNIPAAm. Notably, the hydrophilic and hydrophobic alterations caused by the change in the temperature-responsive property of PNIPAAm-modified interfaces induce temperature-modulated interactions with biomolecules, proteins, and cells. This intrinsic property of PNIPAAm can be effectively used in various biomedical applications, particularly in bioseparation and tissue engineering applications, owing to the functionality of PNIPAAm-modified interfaces based on the temperature modulation of the interaction between PNIPAAm-modified interfaces and biomolecules and cells. This review focuses on PNIPAAm-modified interfaces in terms of preparation method, properties, and their applications. Advances in PNIPAAm-modified interfaces for existing and developing applications are also summarized.