Prosthetic patches for congenital diaphragmatic hernia repair: Surgisis vs Gore-Tex

Patches in Congenital Diaphragmatic Hernia: Systematic Review

OBJECTIVE

This systematic review aims to evaluate current choices in practice and outcomes of biomaterials used in patch repair of congenital diaphragmatic hernia (CDH).

BACKGROUND

Multiple biomaterials, both novel and combinations of pre-existing materials are employed in patch repair of large size CDHs.

METHODS

A literature search was performed across Embase, Medline, Scopus, and Web of Science. Publications that explicitly reported patch repair, material used, and recurrences following CDH repair were selected.

RESULTS

Sixty-three papers were included, presenting data on 4595 patients, of which 1803 (39.2%) were managed using 19 types of patches. Goretex® (GTX) (n=1106) was the most frequently employed patch followed by Dualmesh® (n=267), Surgisis® (n=156), Marlex®/GTX® (n=56), Tutoplast dura® (n=40), Dacron® (n=34), Dacron®/GTX® (n=32), Permacol® (n=24), Teflon® (n=24), Surgisis®/GTX® (n=15), Sauvage® Filamentous Fabric (n=13), Marlex® (n=9), Alloderm® (n=8), Silastic® (n=4), Collagen coated Vicryl® mesh (CCVM) (n=1), Mersilene® (n=1), and MatriStem® (n=1) Biomaterials were further subgrouped as: synthetic nonresorbable (SNOR) (n=1458), natural resorbable (NR) (n=241), combined natural and synthetic nonresorbable (NSNOR) (n=103), and combined natural and synthetic resorbable (NSR) (n=1). The overall recurrence rate for patch repair was 16.6% (n=299). For patch types with n>20, recurrence rate was lowest in GTX/Marlex (3.6%), followed by Teflon (4.2%), Dacron (5.6%), Dualmesh (12.4%), GTX (14.8%), Permacol (16.0%), Tutoplast Dura (17.5%), SIS/GTX (26.7%), SIS (34.6%), and Dacron/GTX (37.5%).When analyzed by biomaterial groups, recurrence was highest in NSR (100%), followed by NR (31.5%), NSNOR (17.5%), and SNOR the least (14.0%).

CONCLUSION

In this cohort, over one-third of CDH were closed using patches. To date, 19 patch types/variations have been employed for CDH closure. GTX is the most popular, employed in over 60% of patients; however, excluding smaller cohorts (n<20), GTX/Marlex is associated with the lowest recurrence rate (3.6%). SNOR was the material type least associated with recurrence, while NSR experienced recurrence in every instance.

Abdominal wall muscle weakness outcomes after split abdominal flap repair of large congenital diaphragmatic hernias in newborn

PURPOSE

Split abdominal wall muscle flap (SAWMF) is a technique to repair large defects in congenital diaphragmatic hernia (CDH). A possible objection to this intervention could be any associated abdominal muscle weakness. Our aim is to analyze the evolution of this abdominal muscle wall weakness.

METHODS

Retrospective review of CDH repair by SAWMF (internal oblique muscle and transverse) from 2004 to 2023 focusing on the evolution of muscle wall weakness.

RESULTS

Eighteen neonates of 148 CDH patients (12,1%) were repaired using SAWMF. Mean gestational age and birth weight were 35.7 ± 3.5 weeks and 2587 ± 816 g. Mean lung-to-head ratio was 1.49 ± 0.28 and 78% liver-up. Seven patients (38%) were prenatally treated by tracheal occlusion. Ninety-four percent of the flaps were used for primary repair and one to repair a recurrence. One patient (5.6%) experienced recurrence. Abdominal muscle wall weakness was present in the form of a bulge. Resolution of weakness at 1, 2 and 3 years was 67%, 89% and 94%, respectively. No patient required treatment for weakness or died.

CONCLUSIONS

Abdominal muscular weakness after a split abdominal wall muscle flap repair is not a limitation for its realization since it is asymptomatic and presents a prompt spontaneous resolution.

LEVEL OF EVIDENCE

IV.

Muscle Flap Technique Safe for On-ECMO Congenital Diaphragmatic Hernia Repair

INTRODUCTION

Prosthetic patches (patch) and muscle flaps (flap) are techniques used for repair of congenital diaphragmatic hernia (CDH) with a large defect unamenable to primary closure. We hypothesized that the flap technique for CDH repair while on extra-corporeal membrane oxygenation (on-ECMO) would have decreased bleeding complications compared to patch due to the hemostatic advantage of native tissue.

METHODS

A single-center retrospective comparative study of patients who underwent on-ECMO CDH repair between 2008 and 2022 was performed.

RESULTS

Fifty-two patients met inclusion criteria: 18 patch (34.6%) and 34 flap (65.4%). There was no difference in CDH severity between groups. On univariate analysis, reoperation for surgical bleeding was lower following flap repair compared to patch (23.5% vs 55.6%, respectively; p = 0.045), 48-h postoperative blood product transfusion was lower after flap repair (132 mL/kg vs 273.5 mL/kg patch; p = 0.006), and two-year survival was increased in the flap repair group compared to patch (53.1% vs 17.7%, respectively; p = 0.036). On multivariate analysis adjusting for CDH side, day on ECMO repaired, and day of life CDH repaired, flap repair was significantly associated with lower five-day postoperative packed red blood cell transfusion amount, improved survival to hospital discharge, and improved two-year survival.

CONCLUSIONS

Our experience suggests that the muscle flap technique for on-ECMO CDH repair is associated with reduced bleeding complications compared to prosthetic patch repair, which may in part be responsible for the improved survival seen in the flap repair group. These results support the flap repair technique as a favored method for on-ECMO CDH repair.

LEVEL OF EVIDENCE

Level III.

Surgical Risk Factors for Delayed Oral Feeding Autonomy in Patients with Left-Sided Congenital Diaphragmatic Hernia

BACKGROUND

Congenital diaphragmatic hernia (CDH) is a rare disease associated with major nutritional and digestive morbidities. Oral feeding autonomy remains a major issue for the care and management of these patients. The aim of this study was to specify the perinatal risk factors of delayed oral feeding autonomy in patients treated for CDH.

METHODS

This monocentric cohort study included 138 patients with CDH. Eighty-four patients were analyzed after the exclusion of 54 patients (11 with delayed postnatal diagnosis, 5 with chromosomal anomaly, 9 with genetic syndrom, 13 with right-sided CDH, and 16 who died before discharge and before oral feeding autonomy was acquired). They were divided into two groups: oral feeding autonomy at initial hospital discharge (group 1, n = 51) and nutritional support at discharge (group 2, n = 33). Antenatal, postnatal, and perisurgical data were analyzed from birth until first hospital discharge. To remove biased or redundant factors related to CDH severity, statistical analysis was adjusted according to the need for a patch repair.

RESULTS

After analysis and adjustment, delayed oral feeding autonomy was not related to observed/expected lung-to-head ratio (LHR o/e), intrathoracic liver and/or stomach position, or operative duration. After adjustment, prophylactic gastrostomy (OR adjusted: 16.3, IC 95%: 3.6-74.4) and surgical reoperation (OR adjusted: 5.1, IC 95% 1.1-23.7) remained significantly associated with delayed oral feeding autonomy.

CONCLUSIONS

Delayed oral feeding autonomy occurred in more than one third of patients with CDH. Both prophylactic gastrostomy and surgical reoperation represent significant risk factors. Bowel obstruction might also impact oral feeding autonomy. Prophylactic gastrostomy seems to be a false "good idea" to prevent failure to thrive. This procedure should be indicated case per case. Bowel obstruction and all surgical reoperations represent decisive events that could impact oral feeding autonomy.

Evaluation of a biodegradable polyurethane patch for repair of diaphragmatic hernia in a rat model: A pilot study

INTRODUCTION

Congenital diaphragmatic hernia (CDH) repair is an area of active research. Large defects requiring patches have a hernia recurrence rate of up to 50%. We designed a biodegradable polyurethane (PU)-based elastic patch that matches the mechanical properties of native diaphragm muscle. We compared the PU patch to a non-biodegradable Gore-Tex™ (polytetrafluoroethylene) patch.

METHODS

The biodegradable polyurethane was synthesized from polycaprolactone, hexadiisocyanate and putrescine, and then processed into fibrous PU patches by electrospinning. Rats underwent 4 mm diaphragmatic hernia (DH) creation via laparotomy followed by immediate repair with Gore-Tex™ (n = 6) or PU (n = 6) patches. Six rats underwent sham laparotomy without DH creation/repair. Diaphragm function was evaluated by fluoroscopy at 1 and 4 weeks. At 4 weeks, animals underwent gross inspection for recurrence and histologic evaluation for inflammatory reaction to the patch materials.

RESULTS

There were no hernia recurrences in either cohort. Gore-Tex™ had limited diaphragm rise compared to sham at 4 weeks (1.3 mm vs 2.9 mm, p = 0.003), but no difference was found between PU and sham (1.7 mm vs 2.9 mm, p = 0.09). There were no differences between PU and Gore-Tex™ at any time point. Both patches formed an inflammatory capsule, with similar thicknesses between cohorts on the abdominal (Gore-Tex™ 0.07 mm vs. PU 0.13 mm, p = 0.39) and thoracic (Gore-Tex™ 0.3 mm vs. PU 0.6 mm, p = 0.09) sides.

CONCLUSION

The biodegradable PU patch allowed for similar diaphragmatic excursion compared to control animals. There were similar inflammatory responses to both patches. Further work is needed to evaluate long-term functional outcomes and further optimize the properties of the novel PU patch in vitro and in vivo.

LEVEL OF EVIDENCE

Level II, Prospective Comparative Study.

Synthetic versus Biological Patches for CDH: A Comparison of Recurrence Rates and Adverse Events, Systematic Review, and Meta-Analysis

OBJECTIVE

 Our systematic review aims to compare recurrence rates and complications of biological versus synthetic patches for the repair of congenital diaphragmatic herniae.

METHODS

 Studies from January 1, 1980 to April 25, 2020, with patients under the age of 16 years and with a minimum 6-month follow-up, were included from MEDLINE, Embase, and Cochrane databases. Funnel plots for recurrence rates were constructed for biological and synthetic patches. Subgroup analysis was performed for recurrence rate at the 1-year time-point and data were gathered on individual adverse events from relevant studies.

RESULTS

 A total of 47 studies with 986 patients (226 biological, 760 synthetic) were included. Funnel plot analysis determined overall recurrence rates of 16.7% for synthetic and 30.3% for biological patches. Subgroup analysis of 493 and 146 patients with synthetic and biological patches, respectively, showed recurrence rates of 9.9 and 26%, respectively.The most commonly used patch types-PTFE (polytetrafluoroethylene) and SIS (small intestinal submucosa)-had 11.5 and 33.3% recurrence, respectively. Adhesive bowel obstruction rates ranged from 4 to 29% in studies that systematically reported it for synthetic, and 7 to 35% for biological patches. Gastroesophageal reflux rates ranged from 25 to 48% in studies that systematically reported it for synthetic, and 21 to 42% for biological patches. Pectus deformity rates were reported as high as 80% for synthetic patches.

CONCLUSION

 Biological patches appear to have higher recurrence rates than synthetic patches, while skeletal deformities are associated more commonly with synthetic patches. Results of biological patches are mainly using SIS and this may overestimate complications of current superior biological patches.

Does creating a dome reduce recurrence in congenital diaphragmatic hernia following patch repair?

PURPOSE

To develop a quantifiable approach to identify a dome shape of the repaired diaphragm using post-operative chest radiograph and to determine if a dome-shaped prosthetic patch repair is associated with a decreased rate of CDH recurrence.

METHODS

We conducted a retrospective review of all neonates evaluated at our institution from January 2004 to August 2017 with left- and right-sided CDH with at least 6 months of follow-up after CDH repair. Patch use, post-operative imaging and postnatal outcomes were analyzed. Neonates with patch repair were divided into two groups based on the presence of a dome. Using postoperative chest radiographs, the presence of a dome was classified as having a vertical-horizontal diaphragm ratio (VHDR) greater than 20%. Primary outcome was CDH recurrence after repair.

RESULTS

We identified 192 neonates who met our inclusion criteria. Cohort survival was 96%, recurrence rate was 15%, 78% had a left-sided CDH; 54% received a patch repair, of which 58% had a type C defect. Of the 104 infants with patch repairs, the CDH recurrence rate was 22% (n = 23) at a median age of 8.5 months (3.8, 20.1). Although neonates with a dome repair had more ECMO use and longer hospital stay, their recurrence rate was about half of those with a non-dome repair (14% vs 28%, p = 0.07).

CONCLUSIONS

A dome-shaped repair may reduce recurrence following prosthetic patch repair of congenital diaphragmatic hernia. A larger, multi-institutional study is needed to statistically validate this clinically significant observation.

TYPE OF STUDY

Retrospective review.

LEVEL OF EVIDENCE

III.

Recurrence of Congenital Diaphragmatic Hernia: Risk Factors, Management, and Future Perspectives

Recurrence is one of the most common surgical complications in Congenital Diaphragmatic Hernia (CDH). It could remain clinically silent for a long time or present as an acute complication week, months, or even years after the primary surgery. Several risk factors have been identified so far. An extended diaphragmatic defect represents one of the leading independent risk factors, together with indirect signs of large defect such as the liver position related to the diaphragm and the use of the prosthetic patch and with the use of a minimally invasive surgical (MIS) approach. However, the exact contribution of each factor and the overall risk of recurrence during the life span still need to be fully understood. This mini-review aims to give an overview of the current knowledge regarding CDH recurrence, focusing on predisposing factors, clinical presentation, management and follow-up of high-risk patients, and future perspectives.

Small Bowel Obstruction After Neonatal Repair of Congenital Diaphragmatic Hernia-Incidence and Risk-Factors Identified in a Large Longitudinal Cohort-Study

OBJECTIVE

In patients with a congenital diaphragmatic hernia (CDH), postoperative small bowel obstruction (SBO) is a life-threatening event. Literature reports an incidence of SBO of 20% and an association with patch repair and ECMO treatment. Adhesions develop due to peritoneal damage and underly various biochemical and cellular processes. This longitudinal cohort study is aimed at identifying the incidence of SBO and the risk factors of surgical, pre-, and postoperative treatment.

METHODS

We evaluated all consecutive CDH survivors born between January 2009 and December 2017 participating in our prospective long-term follow-up program with a standardized protocol.

RESULTS

A total of 337 patients were included, with a median follow-up of 4 years. SBO with various underlying causes was observed in 38 patients (11.3%) and significantly more often after open surgery (OS). The majority of SBOs required surgical intervention (92%). Adhesive SBO (ASBO) was detected as the leading cause in 17 of 28 patients, in whom surgical reports were available. Duration of chest tube insertion [odds ratio (OR) 1.22; 95% CI 1.01-1.46, p = 0.04] was identified as an independent predictor for ASBO in multivariate analysis. Beyond the cut-off value of 16 days, the incidence of serous effusion and chylothorax was higher in patients with ASBO (ASBO/non-SBO: 2/10 vs. 3/139 serous effusion, p = 0.04; 2/10 vs. 13/139 chylothorax, p = 0.27). Type of diaphragmatic reconstruction, abdominal wall closure, or ECMO treatment showed no significant association with ASBO. A protective effect of one or more re-operations has been detected (RR 0.16; 95% CI 0.02-1.17; p = 0.049).

CONCLUSION

Thoracoscopic CDH repair significantly lowers the risk of SBO; however, not every patient is suitable for this approach. GoreTex®-patches do not seem to affect the development of ASBO, while median laparotomy might be more favorable than a subcostal incision. Neonates produce more proinflammatory cytokines and have a reduced anti-inflammatory capacity, which may contribute to the higher incidence of ASBO in patients with a longer duration of chest tube insertion, serous effusion, chylothorax, and to the protective effect of re-operations. In the future, novel therapeutic strategies based on a better understanding of the biochemical and cellular processes involved in the pathophysiology of adhesion formation might contribute to a reduction of peritoneal adhesions and their associated morbidity and mortality.

Surgeon level variation in outcome of repair of congenital diaphragmatic hernia with particular reference to the management of recurrence

INTRODUCTION

The aim of this study is to investigate firstly, the rate of recurrence following primary repair of a congenital diaphragmatic hernia (CDH) and secondly, the rate of recurrence following revisional surgical repair. The primary outcome is rate of recurrence. Secondary outcomes are to establish whether recurrence is related to surgeon, surgeon volume, side of defect, the use of a patch, or a thoracopscopic approach METHODS: All repairs performed in an English regional center over 22 years were recorded. Possible explanatory variables were whether the repair was itself of a recurrence, the surgeon's identity, the surgeon's volume of prior repairs, the side of the defect, the use of a patch.

RESULTS

198 repairs were performed; 170 primary repairs and 28 of recurrences. Failure occurred significantly more commonly among recurrences (32%) than primary repairs (11%), p = 0.005. Failure of the primary repair was significantly more common where a patch was used 8/34 (23%) rather than a sutured repair 10/136 (7%), p = 0.006, or where a thoracoscopic technique was used 4/13 (31%) rather than laparotomy 14/157 (9%) p = 0.01. Failure of the primary repair was unrelated to the identity of the surgeon (Χ² = 5, p = 0.9) or the volume of prior repairs (t = 0.3, p = 0.6). However, failure of repair of a recurrence was significantly related to the surgeon's volume of prior repairs (t = 2.3, p = 0.01) and the identity of the surgeon (Χ² = 17, p = 0.014), but not the use of a patch (Χ² = 1.6, p = 0.2).

CONCLUSIONS

Repair of a recurrence of a CDH has a higher probability of failure than the original repair and is related to both the identity of the surgeon and the prior volume of experience. There is a volume outcome relationship for the repair of recurrence, but not the primary repair of CDH. Our study suggests the repair of recurrence of CDH should be restricted to surgeons with proven outcomes for this procedure.

Biological versus synthetic patch for the repair of congenital diaphragmatic hernia: 8-year experience at a tertiary center

PURPOSE

The aim of this study is to compare outcome between small intestinal submucosal (SIS) and polytetrafluoroethylene (PTFE) patches in patients with congenital diaphragmatic hernia (CDH) with large muscular defects.

MATERIAL AND METHODS

We performed a retrospective review of prospectively collected data of patients who underwent CDH repair from January 2011 to June 2019, with a minimum follow-up of 1 year. Data were collected regarding length of stay (LOS), mortality and recurrence. Kaplan-Meier analyses was used.

RESULTS

In the study period, 195 patients with CDH were admitted, 176 underwent surgical repair and 19 died before surgery. Sixty-two (35%) required a patch. Over the last 5 years, our institution transitioned from the use of all SIS to all PTFE. SIS was used in 18 cases and PTFE in 25. Overall survival rate was 89% (174/195). There was no significant difference regarding LOS and mortality. Nine patients (50%) of SIS and 1 (4%) of PTFE repairs recurred (P < 0.01; log-rank test P <  0.01), with a time course of recurrence of 18 (SD = 13) and 8 months, respectively. Median follow-up was 60 months (SD: 23) for the SIS group and 26 (SD: 10) for the PTFE group.

CONCLUSION

A significant lower recurrence was found using PTFE patches instead of SIS for the repair of large CDH.

LEVEL OF EVIDENCE

Level 3. Retrospective comparative study.

Decellularization of Small Intestinal Submucosa

Small intestinal submucosa (SIS) is the most studied extracellular matrix (ECM) for repair and regeneration of different organs and tissues. Promising results of SIS-ECM as a vascular graft, led scientists to examine its applicability for repairing other tissues. Overall results indicated that SIS grafts induce tissue regeneration and remodeling to almost native condition. Investigating immunomodulatory effects of SIS is another interesting field of research. SIS can be utilized in different forms for multiple clinical and experimental studies. The aim of this chapter is to investigate the decellularization process of SIS and its common clinical application.

Porcine Decellularized Diaphragm Hydrogel: A New Option for Skeletal Muscle Malformations

Hydrogels are biomaterials that, thanks to their unique hydrophilic and biomimetic characteristics, are used to support cell growth and attachment and promote tissue regeneration. The use of decellularized extracellular matrix (dECM) from different tissues or organs significantly demonstrated to be far superior to other types of hydrogel since it recapitulates the native tissue’s ECM composition and bioactivity. Different muscle injuries and malformations require the application of patches or fillers to replenish the defect and boost tissue regeneration. Herein, we develop, produce, and characterize a porcine diaphragmatic dECM-derived hydrogel for diaphragmatic applications. We obtain a tissue-specific biomaterial able to mimic the complex structure of skeletal muscle ECM; we characterize hydrogel properties in terms of biomechanical properties, biocompatibility, and adaptability for in vivo applications. Lastly, we demonstrate that dECM-derived hydrogel obtained from porcine diaphragms can represent a useful biological product for diaphragmatic muscle defect repair when used as relevant acellular stand-alone patch.

A systematic review and meta-analysis of surgical morbidity of primary versus patch repaired congenital diaphragmatic hernia patients

Large studies comparing the surgical outcome of primary versus patch repair in congenital diaphragmatic hernia (CDH) patients are rare. This study aims to evaluate the incidence of surgical complications in both types of CDH repair. PubMed, EMBASE, Cochrane and Web of Science were searched for peer-reviewed articles. Studies on CDH between 1991 and August 2020 were systematically screened and meta-analyses were performed. Primary outcomes of this review were: haemorrhage, chylothorax, recurrences and small bowel obstruction (SBO). A total of 6436 abstracts were screened, after which 25 publications were included (2910 patients). Patch repaired patients have a 2.8 times higher risk on developing a recurrence (20 studies) and a 2.5 times higher risk on developing a chylothorax (five studies). Moreover, they have a two times higher risk on developing a SBO. No studies could be included that evaluated the incidence of surgical haemorrhage between these patients. Although the quality of the studies was relatively low, patch repaired patients have a higher risk on developing a recurrence, chylothorax and small bowel obstruction. Large prospective studies are required to adjust for severity of disease, to reveal the true causative factors in order to minimize the risk on these surgical complications in both types of patients.

Prosthetic meshes for hernia repair: State of art, classification, biomaterials, antimicrobial approaches, and fabrication methods

Worldwide, hernia repair represents one of the most frequent surgical procedures encompassing a global market valued at several billion dollars. This type of surgery usually requires the implantation of a mesh that needs the appropriate chemical, physical and biological properties for the type of repair. This review thus presents a description of the types of hernias, current hernia repair methods, and the state of the art of prosthetic meshes for hernia repair providing the most important meshes used in clinical practice by surgeons working in this area classified according to their biological or chemical nature, morphology and whether bioabsorbable or not. We emphasise the importance of surgical site infection in herniatology, how to deal with this microbial problem, and we go further into the future research lines on the production of advanced antimicrobial meshes to improve hernia repair and prevent microbial infections, including multidrug-resistant strains. A great deal of progress has been made in this biomedical field in the last decade. However, we are still far from an ideal antimicrobial mesh that can also provide excellent integration to the abdominal wall, mechanical performance, low visceral adhesion and minimal inflammatory or foreign body reactions, among many other problems.

Porcine dermal patches as a risk factor for recurrence after congenital diaphragmatic hernia repair

PURPOSE

Recurrence of congenital diaphragmatic hernia (CDH) is a treatment-related morbidity which can be preventable. There is no consensus about the ideal material for diaphragmatic substitution. The aim of our study is to identify if the use of porcine dermis patches increases the risk of CDH recurrence.

METHODS

Retrospective review of medical records of CDH patients treated between 2013 and 2017 in our center was carried out. Demographic, clinical and surgical variables were collected. Regression analysis was performed to identify which factors increase the risk of recurrence.

RESULTS

50 patients entered the study. 94% of the patients had a left CDH, mean observed/expected lung-to-head ratio was 46%. 17 patients underwent a primary closure, the rest a patch closure: 25 Gore-Tex^® and 8 porcine dermis patches were used. Seven patients presented recurrence (14%). Median follow-up time was 3.5 years (1.2-6.2). Univariate analysis revealed that the use of a porcine dermis patch (75%) increased the risk of recurrence compared with Gore-Tex^® patch (4%) and primary closure (0%) p < 0.001 (HR 58.7; IC 95%: 6.9-501.2; p < 0.001).

CONCLUSION

The main risk factor for CDH recurrence is the use of a porcine dermis patch. We do not recommend the use of these patches for CDH repair.

Longitudinal Follow-Up With Radiologic Screening for Recurrence and Secondary Hiatal Hernia in Neonates With Open Repair of Congenital Diaphragmatic Hernia-A Large Prospective, Observational Cohort Study at One Referral Center

Objective: After neonatal repair of congenital diaphragmatic hernia (CDH) recurrence is the most severe surgical complication and reported in up to 50% after patch implantation. Previous studies are difficult to compare due to differences in surgical techniques and retrospective study design and lack of standardized follow-up or radiologic imaging. The aim was to reliably detect complication rates by radiologic screening during longitudinal follow-up after neonatal open repair of CDH and to determine possible risk factors. Methods: At our referral center with standardized treatment algorithm and follow-up program, consecutive neonates were screened for recurrence by radiologic imaging at defined intervals during a 12-year period. Results: 326 neonates with open CDH repair completed follow-up of a minimum of 2 years. 68 patients (21%) received a primary repair, 251 (77%) a broad cone-shaped patch, and 7 a flat patch (2%). Recurrence occurred in 3 patients (0.7%) until discharge and diaphragmatic complications in 28 (8.6%) thereafter. Overall, 38 recurrences and/or secondary hiatal hernias were diagnosed (9% after primary repair, 12.7% after cone-shaped patch; p = 0.53). Diaphragmatic complications were significantly associated with initial defect size (r = 0.26). In multivariate analysis left-sided CDH, an abdominal wall patch and age below 4 years were identified as independent risk factors. Accordingly, relative risks (RRs) were significantly increased [left-sided CDH: 8.5 (p = 0.03); abdominal wall patch: 3.2 (p < 0.001); age ≤4 years: 6.5 (p < 0.002)]. 97% of patients with diaphragmatic complications showed no or nonspecific symptoms and 45% occurred beyond 1 year of age. Conclusions: The long-term complication rate after CDH repair highly depends on surgical technique: a comparatively low recurrence rate seems to be achievable in large defects by implantation of a broad cone-shaped, non-absorbable patch. Longitudinal follow-up with regular radiologic imaging until adolescence is essential to reliably detecting recurrence to prevent acute incarceration and chronic gastrointestinal morbidity with their impact on prognosis. Based on our findings and literature review, a risk-stratified approach to diaphragmatic complications is proposed.

Design and fabrication of polycaprolactone/gelatin composite scaffolds for diaphragmatic muscle reconstruction

Diaphragmatic wall defects caused by congenital disorders or disease remain a major challenge for physicians worldwide. Polymeric patches have been extensively explored within research laboratories and the clinic for soft tissue and diaphragm reconstruction. However, patch usage may be associated with allergic reaction, infection, granulation, and recurrence of the hernia. In this study, we designed and fabricated a porous scaffold using a combination of 3D printing and freeze-drying techniques. A 3D printed polycaprolactone (PCL) mesh was used to reinforcegelatin scaffolds, representing an advantage over previously reported examples since it provides mechanical strength and flexibility. In vitro studies showed that adherent cells were anchorage-dependent and grew as a monolayer attached to the scaffolds. Microscopic observations indicated better cell attachments for the scaffolds with higher gelatin content as compared with the PCL control samples. Tensile testing demonstrated the mechanical strength of samples was significantly greater than adult diaphragm tissue. The biocompatibility of the specimens was investigated in vivo using a subcutaneous implantation method in Bagg albino adult mice for 20 days, with the results indicating superior cellular behavior and attachment on scaffolds containing gelatin in comparison to pure PCL scaffolds, suggesting that the porous PCL/gelatin scaffolds have potential as biodegradable and flexible constructs for diaphragm reconstruction.

Innovative, Stabilizing Self-Expandable Patch for Easier and Safer Thoracoscopic Repair of Congenital Diaphragmatic Hernia

Introduction: Thoracoscopic repair of congenital diaphragmatic hernia (CDH) has become a popular approach and several benefits have been published. Patch closure requires demanding thoracoscopic skills and therefore primary closure with tight sutures is often pursued, which increases the risk of recurrence. The purpose of this study was to create and assess the performance of a new technique for thoracoscopic repair of CDH, which facilitates the surgical procedure. Materials and Methods: An innovative system for thoracoscopic repair of CDH with a novel patch was developed. The patch is self-expandable and offers a traction suture for stabilization, isolating and protecting the viscera. Its performance was assessed and compared with a conventional patch in an inanimate model of the disease through a quantitative and qualitative multivariate analysis. Results: Nine cases of CDH were repaired with each patch. The duration of the procedure was shorter (P < .05) and the level of difficulty was reported to be lower (P < .001) when using the self-expandable patch (SeP). The number of good quality knots was higher and adverse events were less common with this new technique. Conclusions: The stabilizing SeP offers safe and ergonomic performance for thoracoscopic CDH repair, facilitating the surgical technique. The main advantage is that it keeps the viscera isolated into the abdomen while offering a flap on the thoracic side for suturing in a practical manner, minimizing the risk of visceral injury and saving surgical time.

Scaffold-Free Bio-3D Printing Using Spheroids as "Bio-Inks" for Tissue (Re-)Construction and Drug Response Tests

In recent years, scaffold-free bio-3D printing using cell aggregates (spheroids) as "bio-inks" has attracted increasing attention as a method for 3D cell construction. Bio-3D printing uses a technique called the Kenzan method, wherein spheroids are placed one-by-one in a microneedle array (the "Kenzan") using a bio-3D printer. The bio-3D printer is a machine that was developed to perform bio-3D printing automatically. Recently, it has been reported that cell constructs can be produced by a bio-3D printer using spheroids composed of many types of cells and that this can contribute to tissue (re-)construction. This progress report summarizes the production and effectiveness of various cell constructs prepared using bio-3D printers. It also considers the future issues and prospects of various cell constructs obtained by using this method for further development of scaffold-free 3D cell constructions.

Patch repair of congenital diaphragmatic hernia is not at risk of poor outcomes

PURPOSE

Recurrence of congenital diaphragmatic hernia (CDH) was retrospectively evaluated after correction with or without a patch in an institution where tension-free repair is advocated.

METHODS

Demographics and outcomes of patients with a postero-lateral CDH repaired (2000-2016) were analyzed (univariate tests and binary logistic regression adjusting for time since start of study, gender, defect side, liver herniation, patch, surgical approach, absence of postero-lateral rim and length of follow-up).

RESULTS

Of 203 patients, 107 received a patch (P), and 96 were not patched (NP). Groups were not different for gestational age birthweight, gender, defect side and minimally invasive approach rate. Preoperative ECMO incidence (P:29.9% vs. NP:2.1%, p < 0.01), liver herniation (P:57.0% vs. NP:22.9%, p < 0.01) and absence of a postero-lateral rim (P:61.7% vs. NP:8.3%, p < 0.01) were higher in the P group. The mortality rate was 10.8% (P:15.0% vs. NP:6.2%, p = 0.07). Recurrence was not different (P:9.3% vs. NP:4.2%, p = 0.15). Multivariate analysis showed that recurrence was higher after thoracoscopy compared to open (OR = 12.2 [2.2-68], p < 0.01); neither the use of patch (OR = 2.3, [0.5-10.4], p = 0.28) nor any other factors were associated with recurrence.

CONCLUSION

In this single centre series where tension-free repair was advocated, patch repair of CDH was not associated with higher recurrence, though access route was.

TYPE OF STUDY

Cohort Study.

LEVEL OF EVIDENCE

Level III.

Polydopamine Functionalization: A Smart and Efficient Way to Improve Host Responses to e-PTFE Implants

Among the different materials used as protheses for the treatment of Congenital Diaphragmatic Hernia, expanded polytetrafluoroethylene (e-PTFE) plays a leading role owing to its mechanical properties as explained in the first part of this review. However, this material is poorly cell adhesive, which is expected for its contact on the abdominal face, but should display specific tissue adhesion on its thoracic exposed faced. A side specific functionalization method is hence required. The deposition of a nanosized polydopamine film on PTFE is known to be possible but immersion of the e-PTFE membrane in an aerated dopamine solution leads to a functionalization not only on both faces of the membrane but also in its porous volume. The fact that polydopamine also forms at the water/air interface has allowed to transfer a polydopamine film on only one face of the e-PTFE membrane. The deposition method and applications of such Janus like membranes are reviewed in the second part of the review.

Allogenic tissue-specific decellularized scaffolds promote long-term muscle innervation and functional recovery in a surgical diaphragmatic hernia model

Congenital diaphragmatic hernia (CDH) is a neonatal defect in which the diaphragm muscle does not develop properly, thereby raising abdominal organs into the thoracic cavity and impeding lung development and function. Large diaphragmatic defects require correction with prosthetic patches to close the malformation. This treatment leads to a consequent generation of unwelcomed mechanical stress in the repaired diaphragm and hernia recurrences, thereby resulting in high morbidity and significant mortality rates. We proposed a specific diaphragm-derived extracellular matrix (ECM) as a scaffold for the treatment of CDH. To address this strategy, we developed a new surgical CDH mouse model to test the ability of our tissue-specific patch to regenerate damaged diaphragms. Implantation of decellularized diaphragmatic ECM-derived patches demonstrated absence of rejection or hernia recurrence, in contrast to the performance of a commercially available synthetic material. Diaphragm-derived ECM was able to promote the generation of new blood vessels, boost long-term muscle regeneration, and recover host diaphragmatic function. In addition, using a GFP + Schwann cell mouse model, we identified re-innervation of implanted patches. These results demonstrated for the first time that implantation of a tissue-specific biologic scaffold is able to promote a regenerating diaphragm muscle and overcome issues commonly related to the standard use of prosthetic materials. STATEMENT OF SIGNIFICANCE: Large diaphragmatic hernia in paediatric patients require application of artificial patches to close the congenital defect. The use of a muscle-specific decellularized scaffold in substitution of currently used synthetic materials allows new blood vessel growth and nerve regeneration inside the patch, supporting new muscle tissue formation. Furthermore, the presence of a tissue-specific scaffold guaranteed long-term muscle regeneration, improving diaphragm performance to almost complete functional recovery. We believe that diaphragm-derived scaffold will be key player in future pre-clinical studies on large animal models.

Generation of a Functioning and Self-Renewing Diaphragmatic Muscle Construct

Surgical repair of large muscular defects requires the use of autologous graft transfer or prosthetic material. Naturally derived matrices are biocompatible materials obtained by tissue decellularization and are commonly used in clinical practice. Despite promising applications described in the literature, the use of acellular matrices to repair large defects has been only partially successful, highlighting the need for more efficient constructs. Scaffold recellularization by means of tissue engineering may improve not only the structure of the matrix, but also its ability to functionally interact with the host. The development of such a complex construct is challenging, due to the complexity of the native organ architecture and the difficulties in recreating the cellular niche with both proliferative and differentiating potential during growth or after damage. In this study, we tested a mouse decellularized diaphragmatic extracellular matrix (ECM) previously described by our group, for the generation of a cellular skeletal muscle construct with functional features. The decellularized matrix was stored using different conditions to mimic the off‐the‐shelf clinical need. Pediatric human muscle precursors were seeded into the decellularized scaffold, demonstrating proliferation and differentiation capability, giving rise to a functioning three‐dimensional skeletal muscle structure. Furthermore, we exposed the engineered construct to cardiotoxin injury and demonstrated its ability to activate a regenerative response in vitro promoting cell self‐renewal and a positive ECM remodeling. Functional reconstruction of an engineered skeletal muscle with maintenance of a stem cell pool makes this a promising tool toward future clinical applications in diaphragmatic regeneration. stem cells translational medicine2019;8:858&869

Providing direction improves function: Comparison of a radial pore-orientated acellular collagen scaffold to clinical alternatives in a surgically induced rabbit diaphragmatic tissue defect model

Gore-Tex® is a widely used durable patch for repair of congenital diaphragmatic defects yet may result in complications. We compared Gore-Tex with a composite of a radial pore-orientated collagen scaffold (RP-Composite) and clinically used porcine small intestinal submucosa (SIS; Surgisis®) in a rabbit model for diaphragmatic hernia. The growing rabbit mimics the rapid rib cage growth and reherniation rates seen in children. We created and immediately repaired left hemidiaphragmatic defects in 6-week-old rabbits with Gore-Tex, SIS, and an RP-Composite scaffold. An additional group of rabbits had a sham operation. At 90 days, survivors more than doubled in weight. We observed few reherniations or eventrations in Gore-Tex (17%) and RP-Composite (22%) implanted animals. However, SIS failed in all rabbits. Maximum transdiaphragmatic pressure was lower in Gore-Tex (71%) than RP-Composite implanted animals (112%) or sham (134%). Gore-Tex repairs were less compliant than RP-Composite, which behaved as sham diaphragm (p < 0.01). RP-Composite induced less foreign body giant cell reaction than Gore-Tex (p < 0.05) with more collagen deposition (p < 0.001), although there was a tendency for the scaffold to calcify. Unlike Gore-Tex, the compliance of diaphragms reconstructed with RP-Composite scaffolds were comparable with native diaphragm, whereas reherniation rates and transdiaphragmatic pressure measurements were similar.

A finite element analysis of diaphragmatic hernia repair on an animal model

The diaphragm is a mammalian skeletal muscle that plays a fundamental role in the process of respiration. Alteration of its mechanical properties due to a diaphragmatic hernia contributes towards compromising its respiratory functions, leading to the need for surgical intervention to restore the physiological conditions by means of implants. This study aims to assess via numerical modeling biomechanical differences between a diaphragm in healthy conditions and a herniated diaphragm surgically repaired with a polymeric implant, in a mouse model. Finite Element models of healthy and repaired diaphragms are developed from diagnostic images and anatomical samples. The mechanical response of the diaphragmatic tendon is described by assuming an isotropic hyperelastic model. A similar constitutive model is used to define the mechanical behavior of the polymeric implant, while the muscular tissue is modeled by means of a three-element Hill's model, specifically adapted to mouse muscle fibers. The Finite Element Analysis is addressed to simulate diaphragmatic contraction in the eupnea condition, allowing the evaluation of diaphragm deformation in healthy and herniated-repaired conditions. The polymeric implant reduces diaphragm excursion compared to healthy conditions. This explains the possible alteration in the mechanical functionality of the repaired diaphragm. Looking to the surgical treatment of diaphragmatic hernia in human neonatal subjects, this study suggests the implementation of alternative approaches based on the use of biological implants.

Decellularized Diaphragmatic Muscle Drives a Constructive Angiogenic Response In Vivo

Skeletal muscle tissue engineering (TE) aims to efficiently repair large congenital and acquired defects. Biological acellular scaffolds are considered a good tool for TE, as decellularization allows structural preservation of tissue extracellular matrix (ECM) and conservation of its unique cytokine reservoir and the ability to support angiogenesis, cell viability, and proliferation. This represents a major advantage compared to synthetic scaffolds, which can acquire these features only after modification and show limited biocompatibility. In this work, we describe the ability of a skeletal muscle acellular scaffold to promote vascularization both ex vivo and in vivo. Specifically, chicken chorioallantoic membrane assay and protein array confirmed the presence of pro-angiogenic molecules in the decellularized tissue such as HGF, VEGF, and SDF-1α. The acellular muscle was implanted in BL6/J mice both subcutaneously and ortotopically. In the first condition, the ECM-derived scaffold appeared vascularized 7 days post-implantation. When the decellularized diaphragm was ortotopically applied, newly formed blood vessels containing CD31⁺, αSMA⁺, and vWF⁺ cells were visible inside the scaffold. Systemic injection of Evans Blue proved function and perfusion of the new vessels, underlying a tissue-regenerative activation. On the contrary, the implantation of a synthetic matrix made of polytetrafluoroethylene used as control was only surrounded by vWF⁺ cells, with no cell migration inside the scaffold and clear foreign body reaction (giant cells were visible). The molecular profile and the analysis of macrophages confirmed the tendency of the synthetic scaffold to enhance inflammation instead of regeneration. In conclusion, we identified the angiogenic potential of a skeletal muscle-derived acellular scaffold and the pro-regenerative environment activated in vivo, showing clear evidence that the decellularized diaphragm is a suitable candidate for skeletal muscle tissue engineering and regeneration.

Isolation of myogenic progenitor cell population from human placenta: A pilot study

PURPOSE

The purpose of this study was to demonstrate a method of isolating myogenic progenitor cells from human placenta chorionic villi and to confirm the myogenic characteristics of the isolated cells.

METHODS

Cells were isolated from chorionic villi of a second trimester male placenta via a combined enzymatic digestion and explant culture. A morphologically distinct subpopulation of elongated and multinucleated cells was identified. This subpopulation was manually passaged from the explant culture, expanded, and analyzed by fluorescence in situ hybridization (FISH) assay, immunocytochemistry, and flow cytometry. Myogenic characteristics including alignment and fusion were tested by growing these cells on aligned polylactic acid microfibrous scaffold in a fusion media composed of 2% horse serum in Dulbecco's modified Eagle medium/high glucose.

RESULTS

The expanded subpopulation was uniformly positive for integrin α-7. Presence of Y-chromosome by FISH analysis confirmed chorionic villus origin rather than maternal cell contamination. Isolated cells grew, aligned, and fused on the microfibrous scaffold, and they expressed myogenin, desmin, and MHC confirming their myogenic identity.

CONCLUSION

Myogenic progenitor cells can be isolated from human chorionic villi. This opens the possibility for translational and clinical applications using autologous myogenic cells for possible engraftment in treatment of chest and abdominal wall defects.

Minimal modulation of the host immune response to SIS matrix implants by mesenchymal stem cells from the amniotic fluid

PURPOSE

Surgical restoration of soft tissue defects often requires implantable devices. The clinical outcome of the surgery is determined by the properties inherent to the used matrix. Mesenchymal stem cells (MSC) modulate the immune processes after in vivo transplantation and their addition to matrices is associated with constructive remodeling. Herein we evaluate the potential of MSC derived from the amniotic fluid (AF-MSC), an interesting MSC source for cell therapeutic applications in the perinatal period, for immune modulation when added to a biomaterial.

METHODS

We implant cell free small intestinal submucosa (SIS) or SIS seeded with AF-MSC at a density of 1 × 10⁵/cm² subcutaneously at the abdominal wall in immune competent rats. The host immune response is evaluated at 3, 7 and 14 days postoperatively.

RESULTS

The matrix-specific or cellular characteristics are not altered after 24 h of in vitro co-culture of SIS with AF-MSC. The host immune response was not different between animals implanted with cell free or AF-MSC-seeded SIS in terms of cellular infiltration, vascularity, macrophage polarization or scaffold replacement. Profiling the mRNA expression level of inflammatory cytokines at the matrix interface shows a significant reduction in the expression of the pro-inflammatory marker Tnf-α and a trend towards lower iNos expression upon AF-MSC-seeding of the SIS matrix. Anti-inflammatory marker expression does not alter upon cell seeding of matrix implants.

CONCLUSION

We conclude that SIS is a suitable substrate for in vitro culture of AF-MSC and fibroblasts. AF-MSC addition to SIS does not significantly modulate the host immune response after subcutaneous implantation in rats.

Congenital Diaphragmatic hernia - a review

Congenital Diaphragmatic hernia (CDH) is a condition characterized by a defect in the diaphragm leading to protrusion of abdominal contents into the thoracic cavity interfering with normal development of the lungs. The defect may range from a small aperture in the posterior muscle rim to complete absence of diaphragm.

The pathophysiology of CDH is a combination of lung hypoplasia and immaturity associated with persistent pulmonary hypertension of newborn (PPHN) and cardiac dysfunction. Prenatal assessment of lung to head ratio (LHR) and position of the liver by ultrasound are used to diagnose and predict outcomes. Delivery of infants with CDH is recommended close to term gestation. Immediate management at birth includes bowel decompression, avoidance of mask ventilation and endotracheal tube placement if required. The main focus of management includes gentle ventilation, hemodynamic monitoring and treatment of pulmonary hypertension followed by surgery. Although inhaled nitric oxide is not approved by FDA for the treatment of PPHN induced by CDH, it is commonly used.

Extracorporeal membrane oxygenation (ECMO) is typically considered after failure of conventional medical management for infants ≥ 34 weeks’ gestation or with weight >2 kg with CDH and no associated major lethal anomalies. Multiple factors such as prematurity, associated abnormalities, severity of PPHN, type of repair and need for ECMO can affect the survival of an infant with CDH. With advances in the management of CDH, the overall survival has improved and has been reported to be 70-90% in non-ECMO infants and up to 50% in infants who undergo ECMO.

Repair of Postoperative Abdominal Hernia in a Child with Congenital Omphalocele Using Porcine Dermal Matrix

Introduction. Incisional hernias are a common complication appearing after abdominal wall defects reconstruction, with omphalocele and gastroschisis being the most common etiologies in children. Abdominal closure of these defects represents a real challenge for pediatric surgeons with many surgical techniques and various prosthetic materials being used for this purpose. Case Report. We present a case of repair of a postoperative ventral hernia occurring after congenital omphalocele reconstruction in a three-and-a-half-year-old child using an acellular, sterile, porcine dermal mesh. Conclusion. Non-cross-linked acellular porcine dermal matrix is an appropriate mesh used for the reconstruction of abdominal wall defects and their postoperative complications like large ventral hernias with success and preventing their recurrence.

Management of congenital diaphragmatic hernia: A systematic review from the APSA outcomes and evidence based practice committee

OBJECTIVE

Variable management practices complicate the identification of optimal strategies for infants with congenital diaphragmatic hernia (CDH). This review critically appraises the available evidence to provide recommendations.

METHODS

Six questions regarding CDH management were generated. English language articles published between 1980 and 2014 were compiled after searching Medline, Cochrane, Embase and Web of Science. Given the paucity of literature on the subject, all studies irrespective of their rank in the levels of evidence hierarchy were included.

RESULTS

Gentle ventilation with permissive hypercapnia provides the best outcomes. Initial high frequency ventilation may be considered but its overall efficacy is unproven. Routine inhaled nitric oxide (iNO) or other medical adjuncts for acute, severe pulmonary hypertension demonstrate no benefit. Evidence does not support routine administration of pre- or postnatal glucocorticoids. Mode of extracorporeal membrane oxygenation (ECMO) has little bearing on outcomes. While the overall timing of repair does not impact outcomes, early repair on ECMO has benefits. Open repair leads to significantly fewer recurrences. Polytetrafluoroethylene (PTFE) is the most durable patch repair material.

CONCLUSIONS

Limited high-level evidence prevents the development of robust management guidelines for CDH. Prospective, multi-institutional studies are needed to identify best practices and optimize outcomes.

Diaphragm Repair with a Novel Cross-Linked Collagen Biomaterial in a Growing Rabbit Model

Background

Neonates with congenital diaphragmatic hernia and large defects often require patch closure. Acellular collagen matrices (ACM) have been suggested as an alternative to synthetic durable patches as they are remodeled by the host or could also be used for tissue engineering purposes.

Materials and Methods

2.0x1.0 cm diaphragmatic defects were created in 6-weeks old New-Zealand white rabbits. We compared reconstruction with a purpose-designed cross-linked ACM (Matricel) to 4-layer non-cross-linked small intestinal submucosa (SIS) and a 1-layer synthetic Dual Mesh (Gore-Tex). Unoperated animals or animals undergoing primary closure (4/0 polyglecaprone) served as age-matched controls. 60 (n = 25) resp. 90 (n = 17) days later, animals underwent chest x-ray and obduction for gross examination of explants, scoring of adhesion and inflammatory response. Also, uniaxial tensiometry was done, comparing explants to contralateral native diaphragmatic tissue.

Results

Overall weight nearly doubled from 1,554±242 g at surgery to 2,837±265 g at obduction (+84%). X-rays did show rare elevation of the left diaphragm (SIS = 1, Gore-Tex = 1, unoperated control = 1), but no herniation of abdominal organs. 56% of SIS and 10% of Matricel patches degraded with visceral bulging in four (SIS = 3, Matricel = 1). Adhesion scores were limited: 0.5 (Matricel) to 1 (SIS, Gore-Tex) to the left lung (p = 0.008) and 2.5 (Gore-Tex), 3 (SIS) and 4 (Matricel) to the liver (p<0.0001). Tensiometry revealed a reduced bursting strength but normal compliance for SIS. Compliance was reduced in Matricel and Gore-Tex (p<0.01). Inflammatory response was characterized by a more polymorphonuclear cell (SIS) resp. macrophage (Matricel) type of infiltrate (p<0.05). Fibrosis was similar for all groups, except there was less mature collagen deposited to Gore-Tex implants (p<0.05).

Conclusions

Matricel induced a macrophage-dominated inflammatory response, more adhesions, had appropriate strength but a lesser compliance compared to native tissue. The herein investigated ACM is not a viable option for CDH repair.

Controversies in the management of severe congenital diaphragmatic hernia

Despite years of progress in perinatal care, severe congenital diaphragmatic hernia (CDH) remains a clinical challenge. Controversies include almost every facet of clinical care: the definition of severe CDH by prenatal and postnatal criteria, fetal surgical intervention, ventilator management, pulmonary hypertension management, use of extracorporeal membrane oxygenation, surgical considerations, and long-term follow-up. Breakthroughs are likely only possible by sharing of experience, collaboration between institutions and innovative therapies within well-designed multicenter clinical trials.

Organ bioengineering for the newborn

Regenerative medicine has recently been established as an emerging interdisciplinary field focused on the repair; replacement or regeneration of cells, tissues and organs. It involves various disciplines, which are focused on different aspects of the regeneration process such as cell biology, gene therapy, bioengineering, material science and pharmacology. In this article, we will outline progress on tissue engineering of specific tissues and organs relevant to paediatric surgery.

Full thickness abdominal wall defect in growing rats as a model for congenital diaphragmatic hernia prosthetic repair

BACKGROUND

Large congenital diaphragmatic hernia may require prosthetic correction. Acellular collagen matrices were introduced to avoid complications owing to the use of synthetic patches. We tested 3 different ACM for reconstruction of an abdominal wall defect in an animal model that mimics the fast growth during infancy.

METHODS

Pelvisoft® (CR Bard, Covington, GA) and 2 investigational ACM were used for primary reconstruction of a full thickness abdominal wall defect. 3months-old rats (n=26) were allowed to survive for 90days after implantation. Anatomical, tensiometric and histological analyses were performed. Based on good outcomes, we did the same with 1month-old rats (n=54). Unoperated rats were used for obtaining reference tensiometric values of selected native tissues.

RESULTS

Major wound complications were exclusively observed in 1month-old rats. All explants in both groups thinned significantly (p<0.03) and had an elastic modulus increasing over time, far above that from native tissues at 90days of life. Both investigational ACM induced a more vigorous foreign body reaction than Pelvisoft(®).

CONCLUSIONS

The shift from 3 to 1month-old rats was associated with wound complications. Pelvisoft® showed a better biocompatibility than the 2 investigational ACM. Passive biomechanical properties of all explants were still not comparable to that of native tissues.

In Situ Deposition of PLGA Nanofibers via Solution Blow Spinning

Nanofiber mats and scaffolds have been widely investigated for biomedical applications. Commonly fabricated using electrospinning, nanofibers are generated ex situ using an apparatus that requires high voltages and an electrically conductive target. We report the use of solution blow spinning to generate conformal nanofiber mats/meshes on any surface in situ, utilizing only a commercial airbrush and compressed CO₂. Solution and deposition conditions of PLGA nanofibers were optimized and mechanical properties characterized with dynamic mechanical analysis. Nanofiber mat degradation was monitored for morphologic and molecular weight changes in vitro. Biocompatibility of the direct deposition of nanofibers onto two cell lines was demonstrated in vitro and interaction with blood was qualitatively assessed with scanning electron microscopy. A pilot animal study illustrated the wide potential of this technique across multiple surgical applications, including its use as a surgical sealant, hemostatic, and buttress for tissue repair.

Heparinized collagen scaffolds with and without growth factors for the repair of diaphragmatic hernia: construction and in vivo evaluation

A regenerative medicine approach to restore the morphology and function of the diaphragm in congenital diaphragmatic hernia is especially challenging because of the position and flat nature of this organ, allowing cell ingrowth primarily from the perimeter. Use of porous collagen scaffolds for the closure of surgically created diaphragmatic defects in rats has been shown feasible, but better ingrowth of cells, specifically blood vessels and muscle cells, is warranted. To stimulate this process, heparin, a glycosaminoglycan involved in growth factor binding, was covalently bound to porous collagenous scaffolds (14%), with or without vascular endothelial growth factor (VEGF; 0.4 µg/mg scaffold), hepatocyte growth factor (HGF; 0.5 µg/mg scaffold) or a combination of VEGF + HGF (0.2 + 0.5 µg/mg scaffold). All components were located primarily at the outside of scaffolds. Scaffolds were implanted in the diaphragm of rats and evaluated after 2 and 12 weeks. No herniations or eventrations were observed, and in several cases, growth factor-substituted scaffolds showed macroscopically visible blood vessels at the lung site. The addition of heparin led to an accelerated ingrowth of blood vessels at 2 weeks. In all scaffold types, giant cells and immune cells were present primarily at the liver side of the scaffold, and immune cells and individual macrophages at the lung side; these cell types decreased in number from week 2 to week 12. The addition of growth factors did not influence cellular response to the scaffolds, indicating that further optimization with respect to dosage and release profile is needed.

Construction and in vivo evaluation of a dual layered collagenous scaffold with a radial pore structure for repair of the diaphragm

In each organ the extracellular matrix has a specific architecture and composition, adapted to the functional needs of that organ. As cells are known to respond to matrix organization, biomaterials that take into account the specific architecture of the tissues to be regenerated may have an advantage in regenerative medicine. In this study we focussed on the diaphragm, an organ essential for breathing, and consisting of radial oriented skeletal muscle fibres diverging from a central tendon plate. To mimic this structure dual layered collagenous scaffolds were constructed with a radial pore orientation, prepared by inward out freezing, and reinforced by a layer of compressed collagen. Similar scaffolds with a random round pore structure were taken as controls. Scaffolds were first mildly crosslinked by formaldehyde vapour fixation for initial stabilization (13% and 17% crosslinking for the radial and control scaffolds, respectively), and further crosslinked using aqueous 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide (38% and 37% crosslinking, respectively). Scaffolds were implanted into a surgically created diaphragm defect in rats and explanted after 12weeks. Macroscopically, integration of the radial scaffolds with the surrounding diaphragm was better compared with the controls. Cells had infiltrated further into the centre of the scaffolds (P=0.029) and there was a tendency of blood vessels to migrate deeper into the radial scaffolds (P=0.057, compared with controls). Elongated cells (SMA-positive) were aligned with the radial structures. In conclusion, collagenous scaffolds with a stable radial pore structure can be constructed which facilitate cellular in-growth and alignment in vivo.

An evidence-based review of the current treatment of congenital diaphragmatic hernia

Congenital diaphragmatic hernia is a rare but severe condition affecting 1 in 2000 to 3000 newborns with a survival rate of 67%. Although regular antenatal screening allows prenatal diagnosis in many cases, traditionally treatment has been based on postnatal surgical repair. Recent literature has pointed out the survival benefits of initial stabilization and the use of gentle ventilation strategies prior to definitive treatment, shifting the trend from immediate to delayed surgical repair. Advances in fetal intervention have allowed the introduction of fetal endoscopic tracheal occlusion as a method to hasten lung development before birth in order to minimize postnatal morbidity. Despite appropriate treatment, the long-term outcomes of these patients are plagued with numerous complications, associated with the primary pathology and also aggressive therapeutic measures. International centers of excellence have recently come together in an effort to standardize the care of such patients in hopes of maximizing their outcomes.

Regenerative medicine for the respiratory system: distant future or tomorrow's treatment?

Regenerative medicine (RM) is a new field of biomedical science that focuses on the regeneration of tissues and organs and the restoration of organ function. Although regeneration of organ systems such as bone, cartilage, and heart has attracted intense scientific research over recent decades, RM research regarding the respiratory system, including the trachea, the lung proper, and the diaphragm, has lagged behind. However, the last 5 years have witnessed novel approaches and initial clinical applications of tissue-engineered constructs to restore organ structure and function. In this regard, this article briefly addresses the basics of RM and introduces the key elements necessary for tissue regeneration, including (stem) cells, biomaterials, and extracellular matrices. In addition, the current status of the (clinical) application of RM to the respiratory system is discussed, and bottlenecks and recent approaches are identified. For the trachea, several initial clinical studies have been reported and have used various combinations of cells and scaffolds. Although promising, the methods used in these studies require optimization and standardization. For the lung proper, only (stem) cell-based approaches have been probed clinically, but it is becoming apparent that combinations of cells and scaffolds are required to successfully restore the lung's architecture and function. In the case of the diaphragm, clinical applications have focused on the use of decellularized scaffolds, but novel scaffolds, with or without cells, are clearly needed for true regeneration of diaphragmatic tissue. We conclude that respiratory treatment with RM will not be realized tomorrow, but its future looks promising.

Defect-diaphragmatic ratio: a new parameter for assessment of defect size in neonates with congenital diaphragmatic hernia

AIM

The aim of our study is to introduce a new objective method of perioperative evaluation of the size of diaphragmatic defect to enable comparison of results among various centres and methods used for diaphragmatic reconstruction.

MATERIALS AND METHODS

Prospective observational study of neonates with congenital diaphragmatic hernia (CDH) and respiratory distress within 24 h of birth operated on from January 2009 to December 2011. Weight, length, thoracic shape and the diameters of diaphragmatic defect were measured. To determine the relative size of the defect, a defect-diaphragmatic ratio (DDR = defect area:diaphragm area × 100) was calculated. The measured and calculated data were subsequently compared between Gore-Tex patch group (GT) and primary repair group (PR). Mann-Whitney U test was used for statistical analysis.

RESULTS

Forty-seven patients with CDH were admitted during study period. The overall survival rate was 79 % (37/47). Preoperative stabilization was achieved in 85 % (40/47). Survival of operated neonates was 93 % (37/40). Diaphragmatic reconstruction with Gore-Tex patch was used in 7 neonates (17 %), and primary repair in 33 (83 %). Mortality in Gore-Tex group was 29 %; mortality in primary repair group was 3 %. Data of anthropometric measurement were complete in 34 children (5 GT and 29 PR). Significant differences were found between GT group and PR group in the size of diaphragmatic defect with the transverse and sagittal diameters of defect (48.0 ± 5.7 vs. 30.1 ± 5.9, P < 0.00061; 34.0 ± 12.5 vs. 16.0 ± 7.3, P < 0.0022) and DDR (18.29 ± 4.60 vs. 5.77 ± 3.28, P < 0.0005), respectively.

CONCLUSION

The value of DDR as an objective criterion of the extent of diaphragmatic defect was confirmed by the close correlation between DDR and feasibility of primary repair in the study group. This objective assessment of defect size may improve comparing various surgical techniques and results of different centres, and thus facilitates sharing experience with management of neonates with CDH.