Small Intestinal Submucosa Extracellular Matrix Research Articles

PERICARDIAL INJECTION OF MICRONIZED MATRIX BIOMATERIAL FOR POST-INFARCT CARDIAC REPAIR

BACKGROUND Injection of micronized biomaterials into the pericardial space is a potential less invasive approach to enhance post-infarct cardiac repair (Image). We have shown that porcine small intestinal submucosal extracellular matrix (SIS-ECM) biomaterials contain fibroblast growth factor-2 (FGF-2); and epicardial application of a SIS-ECM patch over ischemic myocardium promotes reparative post-infarct cardiac remodeling by upregulating vasculogenesis and downregulating fibrosis. Micronizing SIS-ECM into an injectable platform will allow pericardial delivery without the need for invasive surgery. Herein, we demonstrate improved post-infarct cardiac recovery after delivering micronized SIS-ECM powder into the pericardial space in in mice and we explore cellular mechanisms using three-dimensional fibroblast cultures. METHODS AND RESULTS In an intact pericardium mouse infarct model, coronary ligation (infarct) was performed through an unopened/undisrupted pericardium followed by pericardial injection of micronized SIS-ECM suspended in saline (treatment; n=12) or saline (control; n=10). Pressure-volume loops assessed cardiac function after 28 days. Mice receiving pericardial injection of micronized SIS-ECM had higher ejection fraction, lower ventricular stiffness (end diastolic pressure volume relationship; EDPVR), higher stroke work and higher cardiac output compared to saline control. Improved diastolic function represented by ventricular stiffness is suggestive of attenuated fibrosis and improved ventricular compliance. Three-dimensional cell cultures of mouse 3T3 cell line fibroblasts in collagen matrices assessed cellular response when exposed to either biomaterial-conditioned media with eluted growth factors (treatment) or untreated media (control). Collagen gels contract when fibroblasts take on a profibrotic phenotype, reducing in size on a macroscopic level. Additionally, paracrine activity of fibroblasts is measured using multiplex analysis with focus on angiogenic VEGF protein and fibrotic MMP-2 protease. Collagen gel contraction and MMP-2 release were attenuated by biomaterial factors, suggesting reduced fibrotic activity. Micronized SIS-ECM increased VEGF production from fibroblasts. Adding an FGF-2 inhibitor to biomaterial-conditioned media negated the biomaterial's effects, thereby increasing gel contraction and MMP-2 release, highlighting the key role of FGF-2 in attenuating fibroblast activity. Table 1 contains outcomes from all studies. CONCLUSION Pericardial injection of micronized SIS-ECM promotes reparative fibroblast activity, increases production of angiogenic VEGF protein, and preserves post-infarct cardiac compliance and function. Pericardial injection is a less invasive modality that may facilitate early intervention to attenuate maladaptive post-infarct structural remodeling. Future study into mechanism and large animal infarct models will be required to identify key cellular pathways and develop percutaneous strategies for clinical translation. Injection of micronized biomaterials into the pericardial space is a potential less invasive approach to enhance post-infarct cardiac repair (Image). We have shown that porcine small intestinal submucosal extracellular matrix (SIS-ECM) biomaterials contain fibroblast growth factor-2 (FGF-2); and epicardial application of a SIS-ECM patch over ischemic myocardium promotes reparative post-infarct cardiac remodeling by upregulating vasculogenesis and downregulating fibrosis. Micronizing SIS-ECM into an injectable platform will allow pericardial delivery without the need for invasive surgery. Herein, we demonstrate improved post-infarct cardiac recovery after delivering micronized SIS-ECM powder into the pericardial space in in mice and we explore cellular mechanisms using three-dimensional fibroblast cultures. In an intact pericardium mouse infarct model, coronary ligation (infarct) was performed through an unopened/undisrupted pericardium followed by pericardial injection of micronized SIS-ECM suspended in saline (treatment; n=12) or saline (control; n=10). Pressure-volume loops assessed cardiac function after 28 days. Mice receiving pericardial injection of micronized SIS-ECM had higher ejection fraction, lower ventricular stiffness (end diastolic pressure volume relationship; EDPVR), higher stroke work and higher cardiac output compared to saline control. Improved diastolic function represented by ventricular stiffness is suggestive of attenuated fibrosis and improved ventricular compliance. Three-dimensional cell cultures of mouse 3T3 cell line fibroblasts in collagen matrices assessed cellular response when exposed to either biomaterial-conditioned media with eluted growth factors (treatment) or untreated media (control). Collagen gels contract when fibroblasts take on a profibrotic phenotype, reducing in size on a macroscopic level. Additionally, paracrine activity of fibroblasts is measured using multiplex analysis with focus on angiogenic VEGF protein and fibrotic MMP-2 protease. Collagen gel contraction and MMP-2 release were attenuated by biomaterial factors, suggesting reduced fibrotic activity. Micronized SIS-ECM increased VEGF production from fibroblasts. Adding an FGF-2 inhibitor to biomaterial-conditioned media negated the biomaterial's effects, thereby increasing gel contraction and MMP-2 release, highlighting the key role of FGF-2 in attenuating fibroblast activity. Table 1 contains outcomes from all studies. Pericardial injection of micronized SIS-ECM promotes reparative fibroblast activity, increases production of angiogenic VEGF protein, and preserves post-infarct cardiac compliance and function. Pericardial injection is a less invasive modality that may facilitate early intervention to attenuate maladaptive post-infarct structural remodeling. Future study into mechanism and large animal infarct models will be required to identify key cellular pathways and develop percutaneous strategies for clinical translation.

Novel composite trachea grafts using 3-dimensional printing

ObjectivePorcine-derived small intestine submucosa (SIS) extracellular matrix (ECM) surgical patches claim to have greater regenerative properties compared with dermal extracellular matrices. We hypothesized that using SIS-ECM in a bioengineered composite tracheal graft would allow better incorporation into the native tissue. MethodsTwo types of size-matched polycaprolactone support scaffolds were designed: rigid and flexible. The SIS-ECM was wrapped around the polycaprolactone supports lining the inside and outside of the graft. The grafts were implanted in 4 Yorkshire pigs, replacing an ∼2 cm segment of native trachea. Airway patency was evaluated with computed tomography scans and explanted grafts were examined grossly and histologically. ResultsAll animals survived through the immediate postoperative period. Generally, extraluminal examination showed a smooth transition between native and graft without significant volumetric loss. Animals that received the flexible design survived ∼10 days longer than those that received the rigid design; however, severe perianastomotic intraluminal granulation tissue was observed. The rigid design had less significant intraluminal granulation tissue development at the distal anastomosis, but partial dehiscence had occurred at the proximal anastomosis interrupting graft incorporation. ConclusionsThe generally good extraluminal graft incorporation in our composite tracheal graft highlights some increased regenerative capabilities of SIS-ECM. However, the presence of intraluminal granulation tissue indicates that its use as an off-the-shelf, unaltered substrate in an airway graft is still not ideal. Further research must be conducted to determine whether a modification of the substrate is possible to enhance luminal airway incorporation and to exert control over the mechanisms responsible for granulation tissue development.

Annular Dynamics and Leaflet Geometry in Patch Reconstruction of the Posterior Mitral Leaflet After Adding a Flexible Annuloplasty Ring.

Patch reconstruction of the posterior mitral leaflet using small intestinal submucosa extracellular matrix has been successfully performed in a porcine study. The patch reconstruction, however, resulted in non-physiological systolic widening of the mitral annulus, suggesting the need for an annuloplasty ring. The objective was to characterize the impact on annular dynamics and leaflet geometry of adding a flexible annuloplasty ring to the posterior mitral leaflet patch reconstruction. Measurements were performed in an acute 80-kg porcine model, with seven pigs acting as their own controls. The posterior mitral leaflet was reconstructed with a 2-ply small intestinal submucosa extracellular matrix patch (CorMatrix®). Additionally, a Simulus® Flexible Annuloplasty Ring (Medtronic Inc., Minneapolis, MN, USA) was inserted. Mitral annular dynamics were evaluated using sonomicrometry, and leaflet geometry was described using echocardiography. The annuloplasty ring reduced mitral annular dimensions and restricted cyclic changes in mitral annular area (126 ± 19 vs. 30 ± 13mm2, p < 0.001), septal-lateral and commisure-commisure distances. Ring annuloplasty prevented systolic widening in the mitral annulus after posterior mitral leaflet reconstruction. The annular saddle shape and leaflet coaptation length (8.7 ± 2.3 vs. 9.7 ± 1.3mm, p = 0.221) were comparable before and after ring insertion. The flexible annuloplasty ring resulted in a downsized annulus with restriction of cyclic annular changes in the reconstructed mitral valve. Ring insertion preserved the annular saddle shape and coaptation length. The ring annuloplasty counteracted the non-physiological annular dynamics, and this may improve durability of the posterior mitral leaflet patch reconstruction.

Scaffold derived from GGTA1 and CMAH double knockout pigs elicits only slight inflammation in a gene-edited pig model

Acellular extracellular matrix (ECM) contains α-Gal and N-glycolylneuraminic acid (Neu5Gc) antigens that cause clinical side effects. We prepared porcine cornea and small intestinal submucosa ECM (SIS-ECM) from either wild-type (WT) or knockout (KO) pigs, including GGTA1/CMAH double KO (dKO) and CMAH KO (CMAHKO), through gene editing to eliminate α-Gal and/or Neu5Gc antigens. The quality of the SIS-ECM was confirmed by assessing residual DNA, glycosaminoglycan content and histology. The effects of histopathological and IL-6 responses of SIS-ECM from WT, CMAHKO and dKO pigs were compared to those shown by implanting SIS-ECM into the longissimus of WT and dKO pigs. In the histopathological study, WT and dKO SIS-ECM were simultaneously implanted into WT or dKO pigs. Results indicated granulocyte infiltration but no significant difference between the implanted WT and dKO SIS-ECM, however, multinuclear giant cells were significantly more abundant around WT than dKO SIS-ECM if implanted into dKO pigs. In the IL-6 response study, its concentration was significantly higher in WT SIS-ECM than in dKO SIS-ECM; meanwhile, a moderate level of IL-6 was observed in CMAHKO or WT SIS-ECM implanted into dKO or CMAHKO pigs, respectively. Since dKO SIS-ECM elicits only slight inflammation, we conclude that dKO pigs lacking α-Gal and Neu5Gc can serve as biocompatible SIS-ECM donors or as animal models for testing anthropomorphic immune responses to biomedical devices. Statement of SignificanceXenograft‐derived scaffolds, even acellular scaffolds, encounter the challenges of α-Gal and Neu5Gc nonprotein antigens present in the ECM, including the SIS- and corneal-ECM. Gene-edited pigs with depleted α-Gal and nullified Neu5Gc may represent a valuable source for the procurement of tissues for biomaterial manufacturing. This value is indicated by the evidence that the SIS-ECM prepared from these pigs and not wild-type (WT) animals elicited only slight inflammation histopathologically and serologically if implanted into a double gene-knockout (dKO) pig model with α-Gal and Neu5Gc absent. The ECM prepared from dKO pigs provides a further improvement in biocompatibility, and those animals could be used as a testing model and for precisely evaluating Gal and non-Gal antigen immune responses, regardless of biomaterial or biomedical devices.

Mitral Valve Posterior Leaflet Reconstruction Using Extracellular Matrix: In Vitro Evaluation.

To investigate the anatomical and functional effects of complete surgical reconstruction of the posterior mitral leaflet and associated chordae tendineae with a patch made of 2-ply small intestinal submucosal extracellular matrix in vitro. Seven explanted mitral valves with intact subvalvular apparatus from 80-kg pigs were evaluated in a left heart simulator and served as their own controls. After testing the native valve, the mitral posterior leaflet and associated chordae tendineae were excised and reconstructed by using the 2-ply small intestinal submucosa extracellular matrix patch. The characterization of the reconstruction was based on geometric data from digital images, papillary muscle force, annular tethering force and leaflet pressure force. The reconstructed valves were fully functional without regurgitation, tearing or rupture during incrementally increased pressure from 0 to 120 mmHg. The leaflet areas were preserved after reconstruction, with a normal configuration of the coaptation line. However, the coaptation midpoint moved posteriorly after reconstruction (A2: 15.8 ± 1.4 vs. 18.9 ± 1.5 mm, p = 0.002, diff = 3.1 mm, 95% CI 1.3 to 4.8 mm). The anterior papillary muscle force increased significantly (3.9 vs. 4.6 N, p = 0.029, diff = 0.7 N, 95% CI 0.1 to 1.4 N at 120mmHg) after reconstruction. The posterior papillary muscle force, leaflet pressure force and annular pressure force did not change significantly. In this in vitro model, mitral valve anatomy and function were comparable between the native mitral valve and our new surgical technique for complete reconstruction of the posterior mitral leaflet and associated chordae tendineae. These promising results warrant further in vivo evaluation.

In situ implantable three-dimensional extracellular matrix bioactive composite scaffold for postoperative skin cancer therapy

Despite drastic improvements in surgical excision techniques, tumor recurrence has remained a significant problem over the past decades. In particular, there are unavoidable factors that include intraoperative tissue defects and trauma-related bacterial infections that can persistently induce tumor recurrence after surgical excision. Here, a novel platform was established with an extracellular matrix (ECM) scaffold that innovatively incorporated photothermal (PTT)/chemodynamic therapy (CDT). A decellularized small intestinal submucosa extracellular matrix (dSIS-ECM) was extracted from porcine small intestine and used to generate a polyporous tissue engineering scaffold. In addition, black phosphorus nanosheets (BPNs) were synchronously assembled by polydopamine (PDA) and Ag nanoparticles (Ag NPs) to fabricate a BPNs-PDA@Ag nanosystem. The as-prepared BPNs-PDA@Ag nanosystem was incorporated into the polyporous dSIS-ECM to establish a three-dimensional bioactive composite scaffold (dSIS-BPNs-PDA@Ag) that exhibited broad-spectrum bactericidal effects (over 99.6%) toward the E. coli and S. aureus. Additionally, the dSIS-BPNs-PDA@Ag composite scaffold not only accelerated the regeneration of infected wounds due to the intrinsic bioactive elements of dSIS but also effectively inhibited tumor recurrence by generating hyperthermia and hydroxyl radicals (•OH), which kill local residual tumor cells at the sites of excised tumors. In brief, this work designed an ingenious “all in one” strategy to achieve the integration of regeneration and therapy for future clinical applications. This strategy aims to simultaneously cause effective damage to residual tumor cells and bacterial infections and accelerate the regeneration of tissue defects for postoperative therapy.

The Scaffold Derived from GGTA1 and CMAH Gene Knockout Pigs Provoked Little Inflammatory Responses in a Humanized Pig Model

The attempt to produce a porcine small intestinal submucosa extracellular matrix (SIS-ECM) that is fully biocompatible was made. Samples of SIS-ECM were prepared from either wild-type (WT) or double-gene knockout (dKO) pigs without α-Gal and N-glycolylneuraminic acid (Neu5Gc) antigens. The scaffolds, which were sutured into cuts made in the longissimus muscle of the dKO pigs, were expected to exhibit xeno-reactions through natural antibodies as in a human response. A process was established to manufacture ameliorating acellular porcine SIS-ECM implants with consistent quality characteristics, which were assured by analyzing the level of residual DNA, the glycosaminoglycan content, and histochemical stains. Once implanted, the acellular SIS-ECM from the WT pigs caused a significant increase in serum IL-6 levels in the dKO recipient pigs, indicating a host defense through immune reactions. The levels remained unchanged when preparations from the dKO pigs were used. The results together with pathological evidences suggested that dKO pigs without antigenic response to α-Gal or Neu5Gc can serve as biocompatible SIS-ECM donors or as animal models for testing anthropomorphic immune responses to biomedical devices.

Bilayer pifithrin-α loaded extracellular matrix/PLGA scaffolds for enhanced vascularized bone formation

Small intestinal submucosa extracellular matrix (SIS-ECM) composite materials are catching eyes in tissue engineering but have been rarely studied in bone repair. In this study, we developed the unique bilayer bone scaffolds by assembling decellularized SIS-ECM and poly(lactic-co-glycolic acid) (PLGA) nanofibers through the electrospinning technique. To strengthen the bioactivity of the scaffolds, pifithrin-α (PFTα), a p53 inhibitor that can reduce the repressive function of p53 in osteogenesis, was preloaded in the PLGA electrospinning solution. We found that the resultant SIS-ECM/PLGA/PFTα scaffolds exhibited porous morphology, good biocompatibility, and enhanced osteoinductivity. Specifically, the SIS-ECM/PLGA/PFTα scaffolds could promote the osteogenic differentiation and mineralization of the preosteoblasts MC3T3-E1 in a PFTα does dependent manner in vitro. Furthermore, the SIS-ECM/PLGA/PFTα scaffolds were better than the pure SIS-ECM and SIS-ECM/PLGA scaffolds in terms of vessel and new bone tissue formation after 4 weeks post-implantation in vivo. These overall findings indicated that the bilayer PFTα loaded SIS-ECM/PLGA scaffolds facilitated vascularized bone regeneration, showing promising potential for bone tissue engineering.

Entire mitral reconstruction with porcine extracellular matrix in an acute porcine model

ObjectiveThe objective of our study was to investigate the feasibility of reconstructing the entire mitral valvular and subvalvular apparatus in pigs using a modified tube graft design made of 2-ply small intestinal submucosa extracellular matrix. MethodsThe reconstructions were performed in an acute 80-kg porcine model with 8 pigs, each acting as its own control. A modified tube graft was designed from a sheet of 2-ply small intestinal submucosa extracellular matrix. Before and after mitral valve reconstruction, echocardiography was used to assess mitral regurgitation, left ventricular outflow tract obstruction due to systolic anterior motion, mitral stenosis, leaflet mobility, and leaflet geometry. ResultsThe reconstructed mitral valves were fully functional without any observable echocardiographic signs of regurgitation. We did not observe any left ventricular outflow tract obstruction due to systolic anterior motion nor any mitral valve stenosis, despite a diminished septal-lateral distance after reconstruction. The reconstruction had a reduced tenting area, a reduced coaptation length (9.6 ± 1.7 mm vs 7.9 ± 1.0 mm, P = .010, diff = −1.7 mm, 95% confidence interval, −3.1 to −0.4 mm), and atrial bending of both leaflets. ConclusionsIn this acute porcine study, entire mitral valvular and subvalvular apparatus reconstruction using a modified tube graft design made from 2-ply small intestinal submucosal extracellular matrix was feasible. The 2-ply small intestinal submucosa extracellular matrix could withstand the pressure exerted by the left ventricle without any signs of tearing or rupture. These promising results warrant further assessment of both the annular geometry and the long-term durability.

Histological analysis of failed submucosa patches in congenital cardiac surgery.

Objective Porcine small intestinal submucosa extracellular matrix is a biological substitute used in cardiovascular surgery to correct congenital heart defects. Previous studies with this material have shown satisfactory results. In contrast, there are singular reports of patch-associated complications with CorMatrix small intestinal submucosa extracellular matrix. We report the histopathological findings of explanted extracellular matrix patches that were removed because of early failure in patients with congenital heart defects. Methods Explanted patch materials from 4 patients (aged 9 months to 41 years), who underwent reoperation due to early patch failure, were analyzed. Initial surgery comprised one aortic valve reconstruction, one pulmonary valve reconstruction, one atrioventricular septal defect repair, and one aortic arch enlargement. The interval between operations ranged from 69 to 553 days. Results Residual extracellular matrix patch material was evident at explantation in all cases and presented as a structured eosinophilic and anucleate specimen. In two cases, a local focus of scarring and pseudocartilaginous transformation with evidence of calcification was found. There was no evidence of absorption of patch material in any case, nor repopulation by organized tissue formation. Conclusions Histologic examination of explanted extracellular matrix patches showed no evidence of resorption or relevant repopulation with resident cells nor formation of functional tissue structures. In contrast, a mixed chronic inflammatory infiltration, early signs of calcification, and scarring as well as focal pseudocartilaginous transformation were found. Considering recent reports, close follow-up of patients with extracellular matrix patches is recommended to evaluate the performance of this novel material and detect potential problems.

Safety Evaluation of Autologous Tissue Vaccine Cancer Immunotherapy in a Canine Model.

Previous work in rodent models showed that an autologous tissue vaccine is both a safe and effective approach for treating cancer; however, as a translational step, safety must first be evaluated in a more clinically-relevant model. An autologous immunotherapy produced from resected tumors, was evaluated in a clinically-relevant canine model to assess safety. Ninety-three dogs with spontaneously occurring tumors received vaccination with inactivated autologous tumor tissue combined with an adjuvant of particulate porcine small intestinal submucosa extracellular matrix (SIS-ECM). Patients were followed to assess the occurrence of adverse events, overall survival, and tumor recurrence and/or metastasis. A small number (12%) of patients experienced limited, mild pyrexia, injection site swelling, or lethargy, all resolving without clinical intervention. Autologous whole cell cancer immunotherapy can be used safely in the canine model of cancer and represents a safe approach for the treatment for cancer.

Entire mitral valve reconstruction using porcine extracellular matrix: static in vitro evaluation.

To investigate the feasibility of reconstruction of the entire mitral valve using a tube graft made of 2-ply small intestinal submucosa extracellular matrix in vitro. Seven explanted mitral valves with intact subvalvular apparatus from 80 kg pigs were evaluated in a left heart simulator and served as controls. After testing the native valve, the leaflets and chordae tendineae were explanted, and the 2-ply small intestinal submucosa extracellular matrix (CorMatrix®; Cardiovascular Inc., Alpharetta, GA, USA) tube graft was implanted. The characterization was based on geometric data from digital images, papillary muscle force, annular tethering force and leaflet pressure force. The tube grafts were fully functional without any signs of leakage, tearing or rupture during incrementally increased pressures from 0 mmHg to 120 mmHg. The posterior leaflet moved anteriorly and became larger after reconstruction when compared with the native valve. However, the mid coaptation point was preserved. The anterior papillary muscle force decreased significantly (5.2 N vs 4.4 N, P = 0.022 at 120 mmHg), and the posterior papillary muscle force increased significantly (4.8 N vs 5.6 N, P = 0.017 at 120 mmHg) after reconstruction. The entire mitral valvular and subvalvular reconstruction with a 2-ply small intestinal submucosa extracellular matrix tube graft is feasible in an in vitro model. Our method of reconstruction increased the convexity of the anterior leaflet's coaptation line and significantly redistributed the papillary muscle force towards the posterior papillary muscle. These promising results and the prospect of the entire mitral valvular and subvalvular reconstruction warrant further in vivo evaluations.

Evaluation of cellular ingrowth within porcine extracellular matrix scaffolding in congenital heart disease surgery.

The search for an ideal material for cardiac tissue repair has led to utilization of porcine small intestinal submucosa extracellular matrix (CorMatrix). Here, we examine the histologic features of CorMatrix and the associated cellular growth at a variety of time intervals. Tissues with CorMatrix from ten patients (4 male, 6 female) with ages ranging from 2 weeks to 2 years, and implant duration ranging from 1 week to 2 years were included in this study. Samples for analysis were collected at autopsy. Surgical repair sites included great vessel repair (n=9), atrial septum defect (n=1), coronary vessels (n=1), as well as aortic (n=1) and mitral valve (n=2) leaflets. In all specimens, CorMatrix was composed of dense laminated regions of collagen, without appreciable elastin staining. In most grafts, especially those implanted for extended periods of time, tissue with luminal CD31 positivity covered the intimal surface of the CorMatrix graft. This tissue (neo-intima) consisted of spindled myofibroblasts (SMA) and small CD31 positive vessels with occasional mononuclear cells in a matrix composed of collagen, glycosaminoglycans, and rarely elastin, after extended periods of implantation. These features were readily identified in patients as early as 1 month after CorMatrix implantation. The matrix comprising the CorMatrix itself remained largely acellular, despite implantation times up to 2 years, with degradation of the graft material. We provide a framework for histologic expectations when evaluating explanted CorMatrix grafts. In this regard, the CorMatrix matrix is likely to remain acellular without significant elastin deposition, whereas the intimal and adventitial surfaces become coated by proliferating cells in a novel matrix of collagen and glycosaminoglycans.

Diverse preparation methods for small intestinal submucosa (SIS): Decellularization, components, and structure.

The native extracellular matrix (ECM) biomaterial derived from small intestinal submucosa (SIS) is widely applied in tissue engineering for tissue repair and regeneration. SIS ECM is obtained through physical and chemical methods to remove the intrinsic cells, which would otherwise cause adverse immune reactions when the SIS ECM is implanted into the host body. Several research teams have reported diverse SIS decellularization methods. However, there was no consensus on the criteria to be used for the decellularization methods for SIS and further research on the mechanism action of SIS is needed for comprehensive detection of the biological composition. In this present study, we used three reported methods to prepare SIS and compared their effects on decellularization and the remaining biological components, microstructure and cytocompatibility. SIS prepared by the three kinds of decellularization methods all achieved the recommended criteria, had good biocompatibility and retained most active components. Nevertheless, regardless of which decellularization method was used, the microstructure and bioactive components of the prepared SIS were damaged in varying degrees. We recommend that researchers need to select a decellularization method that would be appropriate to use according to their research purposes. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 689-697, 2019.

SIS-ECM Laden with GMSC-Derived Exosomes Promote Taste Bud Regeneration

Oral cancer has a high annual incidence rate all over the world, and the tongue is the most frequently affected anatomic structure. The current standard care is ablative surgery of malignant neoplasm, followed by tongue reconstruction with free flap. However, such reconstructive modalities with postsurgery radiotherapy or chemotherapy can hardly support the functional recovery of the tongue—particularly, functional taste bud regeneration—in reconstructed areas, thus seriously affecting patients’ prognosis and life quality. Using a critical-sized tongue defect model in rats, we show that combinatory transplantation of small intestinal submucosa–extracellular matrix (SIS-ECM) with gingival mesenchymal stem cells (GMSCs) or their derivative exosomes promoted tongue lingual papillae recovery and taste bud regeneration as evidenced by increased expression of CK14, CK8, and markers for type I, II, and III taste bud cells (NTPdase 2, PLC-β2, and AADC, respectively). In addition, our results indicate that GMSCs or their derivative exosomes could increase BDNF expression, a growth factor that plays an important role in the proliferation and differentiation of epithelial basal progenitor cells into taste bud cells. Meanwhile, we showed an elevated expression level of Shh—which is essential for development, homeostasis, and maintenance of the taste bud organ—in wounded areas of the tongue among animals treated with GMSC/SIS-ECM or exosome/SIS-ECM as compared with SIS-ECM control. Moreover, our data show that GMSCs or their derivative exosomes promoted innervation of regenerated taste buds, as evidenced by elevated expressions of neurofilament and P2X3 at the injury areas. Together, our findings indicate that GMSC/SIS-ECM and exosome/SIS-ECM constructs can facilitate taste bud regeneration and reinnervation with promising potential application in postsurgery tongue reconstruction of patients with tongue cancer.

Amino acid-based Poly(ester urea) copolymer films for hernia-repair applications

The use of degradable materials is required to address current performance and functionality shortcomings from biologically-derived tissues and non-resorbable synthetic materials used for hernia mesh repair applications. Herein a series of degradable l-valine-co-l-phenylalanine poly(ester urea) (PEU) copolymers were investigated for soft-tissue repair. Poly[(1-VAL-8)0.7-co-(1-PHE-6)0.3] showed the highest uniaxial mechanical properties (332.5 ± 3.5 MPa). Additionally, l-valine-co-l-phenylalanine poly(ester urea)s were blade coated on small intestine submucosa extracellular matrix (SIS-ECM) and found to enhance the burst test mechanical properties of SIS-ECM in composite films (force at break between 102.6 ± 6.5–151.4 ± 11.3 N). Free standing films of l-valine-co-l-phenylalanine PEUs were found to have superior extension at break when compared to SIS-ECM (averages between 1.2 and 1.9 cm and 1.2 cm respectively). Fibroblast (L-929) spreading, proliferation, and improved attachment over control were observed without toxicity in vitro, while a reduced inflammatory response at both 7 and 14 days post-implant was observed for poly[(1-VAL-8)⁠0.7-co-(1-PHE-6)⁠0.3] when compared to polypropylene in an in vivo rat hernia model. These results support the use of PEU copolymers as free-standing films or as composite materials in soft-tissue applications for hernia-repair.

Mitral valve posterior leaflet reconstruction using extracellular matrix: an acute porcine study.

To investigate mitral valve posterior leaflet and subvalvular reconstruction using a 2-ply small intestinal submucosal extracellular matrix sheet. Mitral valve posterior leaflet and subvalvular reconstruction was characterized in an acute 80-kg porcine model with 7 pigs acting as their own controls. The characterization was based on pressure catheter measurements of pressure differences to identify mitral regurgitation, stenosis and systolic anterior motion. Furthermore, echocardiography was used for the evaluation of leaflet mobility and geometry, whereas sonomicrometry was used to describe annular and subvalvular geometry. The reconstructed mitral valve was fully functional without any signs of regurgitation (peak left atrial pressure for baseline and reconstruction 12 ± 2 mmHg vs 11 ± 2 mmHg, P = 0.550), mitral valve stenosis (mean pressure difference across the mitral valve 4.8 ± 2.3 mmHg vs 4.1 ± 2.3 mmHg, P = 0.589) or systolic anterior motion. The echocardiographic characterization revealed septal-lateral downsizing, reduced tenting area, increased coaptation length (6.0 ± 0.6 mm vs 8.7 ± 2.3 mm, P = 0.002) and an atrial bend of the reconstructed posterior leaflet. A ballooning effect of the patch material was present at the posterior annular segment. Mitral valve posterior leaflet and subvalvular reconstruction using a 2-ply small intestinal submucosal extracellular matrix sheet as patch material was possible in an acute porcine model. The reconstructed mitral valve was fully functional without signs of mitral valve stenosis, valve regurgitation, stenosis or systolic anterior motion. The ballooning appearance of the patch material might, however, constitute an altered leaflet stress distribution in this area.

Use of Decellularised Porcine Intestinal Submucosa Extracellular Matrix in Airway Reconstruction to Enable Lung-sparing Oncological Surgery

Background: Reconstruction of the airways following tracheal or lung-sparing oncological surgery is challenging. A novel approach is the use of bioscaffolds, which allow regeneration of respiratory epithelium and eliminate the need for immunosuppression. Initial experiences with decellularised porcine small intestine submucosa extracellular matrix (CorMatrix) as a scaffold for vascular and cardiac surgery have been encouraging. Its properties are potentially suitable for airway reconstruction.

P3.16-052 Use of Decellularised Porcine Intestinal Submucosa Extracellular Matrix in Airway Reconstruction to Enable Lung-Sparing Oncological Surgery

Reconstruction of the airways following tracheal resection, tracheo-oesophageal complications and lung-sparing oncological surgery is challenging. Airway reconstruction materials ideally must possess balanced properties of rigidity, flexibility and have an intact surface of epithelium to maintain a functional airway. A novel approach is the use of bio-scaffolds which allow regeneration of respiratory epithelium and eliminate the need for immunosuppressive treatment. Initial experiences with decellularised porcine small intestine submucosa extracellular matrix (CorMatrix®) as a scaffold for vascular, cardiac and pericardial tissue repair and reconstruction has been encouraging. The properties of extracellular matrix are potentially suitable for airway reconstruction. We initially used the bio-scaffold for repairing tracheal defects and tracheo-oesophageal fistulae (n=6). We then extended its use to reconstruct distal airways to facilitate lung-sparing oncologic resections of intermediate grade lung tumours (n=3). These patients would otherwise have required pneumonectomy (Case 1 and 2) or bi-lobectomy in a patient with borderline lung function (Case 3). We describe our experience using extracellular matrix for airway reconstruction in lung-sparing oncological surgery. Three patients underwent complex sleeve resections with varying degrees of bronchial airway reconstruction using extracellular matrix. The lung tumours were: (1) muco-epidermoid tumour of the left upper lobe and left main bronchus; (2) typical carcinoid of the right main bronchus; (3) typical carcinoid of the intermediate bronchus and right middle lobe. All patients underwent frozen section pathology examination at the time of surgery and formal histology confirmed pT1N0 and R0 resection status. There were no perioperative complications. All patients underwent bronchoscopy prior to discharge and serial bronchoscopies were carried out 6 weeks, 3 months and at >1 year. All patients had complete integration of the scaffold by epithelialisation and the patch was not evident at 3 months. All segmental bronchi were widely patent. At 18 months there was no tumour recurrence. The use of decellularised porcine intestinal submucosa extracellular matrix (CorMatrix®) as a bio-scaffold is safe and shows remarkable epithelialisation and integrity. It is an option for airway reconstruction to facilitate lung-sparing surgery without compromising oncologic margins.

Transplantation of Isl1+ cardiac progenitor cells in small intestinal submucosa improves infarcted heart function

BackgroundApplication of cardiac stem cells combined with biomaterial scaffold is a promising therapeutic strategy for heart repair after myocardial infarction. However, the optimal cell types and biomaterials remain elusive.MethodsIn this study, we seeded Isl1+ embryonic cardiac progenitor cells (CPCs) into decellularized porcine small intestinal submucosa extracellular matrix (SIS-ECM) to assess the therapeutic potential of Isl1+ CPCs and the biocompatibility of SIS-ECM with these cells.ResultsWe observed that SIS-ECM supported the viability and attachment of Isl1+ CPCs. Importantly, Isl1+ CPCs differentiated into cardiomyocytes and endothelial cells 7 days after seeding into SIS-ECM. In addition, SIS-ECM with CPC-derived cardiomyocytes showed spontaneous contraction and responded to β-adrenergic stimulation. Next, patches of SIS-ECM seeded with CPCs for 7 days were transplanted onto the outer surface of infarcted myocardium in mice. Four weeks after transplantation, the patches were tightly attached to the surface of the host myocardium and remained viable. Transplantation of patches improved cardiac function, decreased the left ventricular myocardial scarring area, and reduced fibrosis and heart failure.ConclusionsTransplantation of Isl1+ CPCs seeded in SIS-ECM represents an effective approach for cell-based heart therapy.