Fibrochondrogenesis of free intraarticular small intestinal submucosa scaffolds

Naturally occurring biomaterials, such as small intestine submucosa (SIS), are attractive as potential scaffolds for engineering various tissue types. The aim of this study was to determine whether acellular SIS scaffolds can support cell attachment and ingrowth in a diarthroadial joint without significant intraarticular hemorrhage. Disks of porcine SIS were arthoscopically implanted freely within a randomized knee joint of 21 dogs and harvested 1, 2, 3, and 6 weeks postoperatively. Harvested disks were assessed for gross and histologic appearance, cellular infiltration, and immunoreactivity of collagenase and collagen types I and II. Knee synovium and synovial fluid were also evaluated. All disks were thickened and opacified at harvest. Eleven disks (52%) had adhered to intraarticular tissues and cellular infiltration into the disks was positively correlated with tissue adherence. Further, tissue adherence was positively correlated with duration of intraarticular implantation. Five disks (24%) contained focal areas of homogeneous extracellular matrix. A trend toward more collagenase immunoreactivity was noted in the 3-week disks. Collagen type I was present in remaining SIS and extracellular matrix associated with infiltrated cells. Placed freely within a joint, acellular SIS disks underwent cellular and extracellular matrix modification resulting in fibrocartilage-like tissue. Utilization of SIS as a scaffold for intraarticular tissue-engineering applications is supported as cytoconductivity, appropriate residence time, and absence of untoward effects of implantation are desirable criteria for a tissue-engineering biomaterial.     

Physical characteristics of small intestinal submucosa scaffolds are location-dependent

Using biodegradable scaffolds as an alternative to engineer new tissues has become an attractive candidate in various transplantation protocols. In particular, small intestinal submucosa (SIS), a dense connective matrix harvested from the small intestine, has gained attention due to a number of favorable properties. However, use of SIS is constrained by obtaining reliable, reproducible products in large-scale preparations that affect the regenerative process. To better understand the heterogeneous nature of SIS, this study focused on evaluating the location-dependent alterations in the physical characteristics of the matrices harvested from distal and proximal ends and processed in-house (referred as hand-made). Additionally, results were compared with a commercially available machine-made Cook SIS. Tensile properties during monotonic loading and cyclical loading were compared in wet conditions. Furthermore, permeability of these membranes to urea was analyzed using a custom-built chamber, and the microarchitecture was analyzed via scanning electron microscopy. These results showed that distal samples were more elastic and less permeable to urea relative to other samples. However, permeability in each sample was direction-dependent, that is, mucosal to serosal direction was less permeable compared to sorasal to mucosal direction in all the samples. Cook SIS was more susceptible to cyclical loading and had a shorter range of load carrying capacity. In summary, results show that physical characteristics of SIS are location-dependent.     

Biaxial mechanical properties of muscle-derived cell seeded small intestinal submucosa for bladder wall reconstitution

Bladder wall replacement remains a challenging problem for urological surgery due to leakage, infection, stone formation, and extensive time needed for tissue regeneration. To explore the feasibility of producing a more functional biomaterial for bladder reconstitution, we incorporated muscle-derived cells (MDC) into small intestinal submucosa (SIS) scaffolds. MDC were harvested from mice hindleg muscle, transfected with a plasmid encoding for beta-galactosidase, and placed into single-layer SIS cell culture inserts. Twenty-five MDC and/or SIS specimens were incubated at 37 degrees C for either 10 or 20 days. After harvesting, mechanical properties were characterized using biaxial testing, and the areal strain under 1 MPa peak stress used to quantify tissue compliance. Histological results indicated that MDC migrated throughout the SIS after 20 days. The mean (+/-SE) areal strain of the 0 day control group was 0.182 +/- 0.027 (n=5). After 10 days incubation, the mean (+/-SE) areal strain in MDC/SIS was 0.247 +/- 0.014 (n=5) compared to 10 day control SIS 0.200 +/- 0.024 (n=6). After 20 days incubation, the mean areal strain of MDC/SIS was 0.255 +/- 0.019 (n=5) compared to control SIS 0.170 +/- 0.025 (n=5). Both 10 and 20 days seeded groups were significantly different (p=0.027) than that of incubated SIS alone, but were not different from each other. These results suggest that MDC growth was supported by SIS and that initial remodeling of the SIS ECM had occurred within the first 10 days of incubation, but may have slowed once the MDC had grown to confluence within the SIS.     

Bladder regeneration with cell-seeded small intestinal submucosa

This study was performed to determine the regenerative properties of smooth muscle cells (SMCs) and urothelial cells (UCs) seeded on small intestinal submucosa (SIS), utilizing a nude mouse model. Human bladder SMCs and UCs were seeded on SIS in a layered coculture fashion. Cell-seeded SIS grafts (1 x 1 cm(2)) were maintained in a CO(2) incubator for 14 days and subsequently folded with the seeded cells facing the lumenal side and implanted subcutaneously into the flanks of nude mice (n = 20). Unseeded SIS grafts were implanted into the contralateral flanks of the mice to serve as controls. Grafts were harvested at 4, 8, and 12 weeks after implantation. By 12 weeks, layered urothelium with a central lumen was noted with early smooth muscle bundle formation peripherally. At each time point, the regenerated SMCs stained positive for alpha-smooth muscle actin, and the UCs stained positive for cytokeratin AE1/AE3. The control group demonstrated no evidence of organized bladder regeneration. This study demonstrates the potential for cell-seeded SIS to induce organized bladder regeneration in vivo. This also provides the basis for additional work utilizing seeded SIS grafts for bladder augmentation.     

兔小肠黏膜下层与软骨细胞体外培养

目的观察软骨细胞在兔小肠黏膜下层(SIS)上的生长特性,为使SIS作为软骨组织工程化的载体打下基础。方法用物理和化学方法处理兔小肠黏膜下层,将不同浓度的兔软骨细胞与SIS进行体外共培养,分别进行组织学、相差显微镜和扫描电镜观察。结果经物理和化学处理的SIS纯度高、孔隙多,胶原纤维未受损;软骨细胞在SIS材料上生长、黏附、增殖,并能长入材料的孔隙内,分泌大量的细胞外基质成分。结论SIS细胞相容性良好,不影响软骨细胞的形态,对细胞生长和功能表达无抑制作用,是一种较理想的软骨细胞载体。     

猪小肠黏膜下基质海绵的制备

 BACKGROUND: Studies have found that small intestinal submucosa that is directly implanted into the lesion cannot effectively promote cell growth and differentiation in vivo and in vitro, because of its small pore size and poor permeability.     

脱细胞猪小肠黏膜下层的组织相容性

目的:研究脱细胞猪小肠黏膜下层(small intestinal submucosa,SIS)的组织相容性。方法:酶消化联合去垢剂制备脱细胞猪SIS。将其植入SD大鼠脊柱旁肌肉内,组织学检测植入后不同时间(1、2和4周)样品周围组织反应。另取乳胶植入,做为阳性对照。结果:经脱细胞处理后,猪SIS仅存纤维结构,未见细胞残留。植入后1周,脱细胞SIS形态完整,可见宿主细胞(成纤维细胞和炎性细胞)长入。2周时,可见脱细胞SIS断裂。至4周时,脱细胞SIS降解,新生细胞外基质形成,并可见毛细血管样结构。随植入时间的延长,炎性细胞逐渐减少。在不同时间点,乳胶均可完整取出,未见宿主细胞长入,其周围形成纤维囊。结论:提示脱细胞猪SIS具有良好的组织相容性。     

小肠黏膜下层在组织修复中的应用

小肠黏膜下层(SIS)已广泛应用于多种组织如膀胱、肌腱、韧带、硬脑膜和血管等的修复,具有部位特异的组织再生能力,在部分组织缺损的修复中,可获得结构和功能上的重建,但在某些组织如输尿管也存在粘连与功能不能重建的问题,尚需进一步的研究。SIS可望作为生物材料广泛应用于组织修复。     

Endothelial cell adherence to small intestinal submucosa: an acellular bioscaffold

Degradable biomaterials to be used as scaffolds for tissue repair will ideally be able to support new blood vessel growth. The present study evaluated the adherence of human dermal microvascular endothelial cells (HMECs) to an acellular resorbable scaffold material derived from the small intestinal submucosa (SIS). HMECs were exposed to hydrated and dehydrated forms of SIS and to plastic surfaces coated with one of four different known components of the SIS extracellular matrix: collagen Type I, collagen Type IV, fibronectin, and laminin. Results showed that adherence of HMECs to hydrated SIS was greater than to any of the other tested surfaces (P < 0.05). Exposure of HMECs to either soluble collagen Type IV or soluble fibronectin prior to exposure of these cells to hydrated SIS showed only partial inhibition of HMEC attachment. We conclude that HMECs find hydrated SIS to be a suitable substrate for adherence and that dehydration of SIS adversely affects the ability of HMECs to adhere in vitro. The cause of HMEC adherence to SIS appears to be a combination of both its composition and architecture.     

兔许旺细胞与猪小肠黏膜下层的体外复合培养

背景：国内外研究以大鼠许旺细胞与小肠黏膜下层复合修复神经缺损,取得了较好结果。 目的：观察兔许旺细胞与猪小肠黏膜下层体外共培养的生物相容性。 方法：采用分步酶消化法分离培养新西兰大白兔许旺细胞,取第3代许旺细胞接种在猪小肠黏膜下层上。 结果与结论：①苏木精-伊红染色：复合培养24 h后细胞在材料上良好黏附。1周时部分细胞在猪小肠黏膜下层基质层表面呈单层生长,细胞扁平,细胞核呈长梭形,细胞间连接紧密。2周后,细胞呈多层生长。②扫描电镜：复合培养2 d,细胞黏附于材料表面并伸展,细胞体呈纺锤形,从胞体伸出两根细长突起,相邻细胞的突起首尾相接连成细胞链或融合或交联或在纤维的侧方平行生长;1周后细胞在材料上大量增殖,呈串珠链黏附于支架上,类似于神经中的Bunger带。表明小肠黏膜下层与许旺细胞有良好的相容性。     

Bupivacaine-enhanced small intestinal submucosa biomaterial as a hernia repair device

Management of post-surgical pain following herniorrhaphy remains a clinical challenge and novel methods to deliver analgesic compounds could be of great benefit. Because there is great interest in the use of natural biomaterials for hernia repair, we investigated the biocompatibility of a natural biomaterial, porcine small intestinal submucosa (SIS), which was impregnated with bupivacaine (SIS-B) via immersion in a solution of poly(lactic-co-glycolic acid) (PLGA). Groups of Sprague Dawley rats underwent surgical creation of a ventral abdominal wall defect with subsequent repair using either SIS or SIS-B. Analysis of serial blood samples showed peak bupivacaine levels (83?ng/mL) were achieved 16?h after implantation of SIS-B. One month after surgery, the rats were euthanized and implant sites harvested for mechanical strength testing and histological analysis. At the time of necropsy, adhesion extent and tenacity was greater in SIS-B rats, with 90% of SIS-B rats have adhesion to the implant site compared to only 75% of SIS rats. Microscopically, SIS implant sites were characterized by small amounts of residual SIS surrounded by mild-to-moderate chronic inflammation. In contrast, rats treated with SIS-B, residual SIS-B was surrounded by a ring of acute inflammatory cells and an outer ring of chronic inflammatory cells, possibly due to bupivacaine or residual PLGA. Mechanical strength testing of the harvested implant sites showed no significant (p?≤?0.05) difference between SIS and SIS-B implants. In summary, bupivacaine is readily elaborated from SIS-B; and impregnation of SIS with bupivacaine does not substantially alter the biocompatibility of the biomaterial or its mechanical strength following implantation.     

小肠黏膜下层与滑膜间充质干细胞的组织相容性

背景：小肠黏膜下层有抗微生物活性、良好的生物相容性及生物力学性能,能在体内快速降解,与半月板纤维软骨细胞的胞外基质相近。 目的：观察小肠黏膜下层与滑膜间充质干细胞是否有良好的组织相容性。 方法：先后采用物理方法与化学方法处理猪小肠黏膜下层,并进行苏木精-伊红染色和扫描电镜观察。制备小肠黏膜下层浸提液,行以下实验：①热源实验：在新西兰大白兔耳缘静脉注射小肠黏膜下层浸提液。②皮肤致敏实验：在新西兰大白兔背部皮内分别注射小肠黏膜下层浸提液、多聚甲醛溶液及生理盐水。③全身毒性实验：在新西兰大白兔耳缘静脉分别注射小肠黏膜下层浸提液与生理盐水。将小肠黏膜下层与成骨诱导的兔滑膜间充质干细胞共培养,以小肠黏膜下层单独培养为对照。 结果与结论：经物理处理过的小肠黏膜下层表面仍然存在小肠黏膜上皮细胞、脂肪细胞和一些其他细胞黏附;经化学方法处理后其残留的细胞数量明显减少,但主要结构和成分未被改变。小肠黏膜下层黏膜面较肌层面光滑,无细胞残留,表面纤维组织交错形成疏松的三维网状立体结构,孔隙率为80%。小肠黏膜下层是一种无毒、无刺激、无免疫原性,生物相容性很好的生物材料,与兔滑膜间充质干细胞具有良好的组织相容性。     

注射型猪小肠黏膜下层与脂肪间充质干细胞的体外共培养

BACKGROUND: The decellularized porcine small intestinal submucosa is a kind of bioactive extracellular matrix, which is mainly composed of collagen, glycoprotein, proteoglycan and rich in collagen, glycosaminoglycan and various growth factors, and these components play an important role in promoting the differentiation and proliferation of tissue cells. OBJECTIVE: To prepare the injectable small intestinal submucosa and to investigate its co-culture with rat adipose-derived mesenchymal stem cells in vitro. METHODS: The injectable small intestinal submucosa and rat adipose-derived stem cells were prepared. Cell counting kit-8 test for cell proliferation: Passage 3 adipose-derived stem cells were seeded onto the injectable small intestinal submucosa (experimental group) and cells cultured under normal condition as control group. The cell proliferation was observed at 1, 3, 5 and 7 days of incubation. Live/dead staining test for the survival of cells: Passage 3 adipose-derived stem cells were respectively cultured in the injectable small intestinal submucosa extracts (experimental group) and complete culture medium (control group). Cell survival was determined at 1, 3, 5 and 7 days of culture. RESULTS AND CONCLUSION: Scanning electron microscope oval and strip adipose- derived stem cells adhered onto the material. The absorbance values in the experimental group were higher than those in the control group at 1 and 5 days of incubation (P < 0.05). Cell survival: The number of cells appeared to be in a rising trend with time in both two groups; after 1-day co-culture, all cells in the two groups survived. Then dead cells appeared in both two groups, showing no significant difference. These results show that the injectable small intestinal submucosa exhibits a good cytocompatibility.      

Electrospun PCL/Gelatin composite fibrous scaffolds: mechanical properties and cellular responses

Electrospinning of hybrid polymer has gained widespread interest by taking advantages of the biological property of the natural polymer and the mechanical property of the synthetic polymer. However, the effect of the blend ratio on the above two properties has been less reported despite the importance to balance these two properties in various tissue engineering applications. To this aim, we investigated the electrospun PCL/Gelatin composite fibrous scaffolds with different blend ratios of 4:1, 2:1, 1:1, 1:2, 1:4, respectively. The morphology of the electrospun samples was observed by SEM and the result showed that the fiber diameter distribution became more uniform with the increase of the gelatin content. The mechanical testing results indicated that the 2:1 PCL/Gelatin sample had both the highest tensile strength of 3.7 MPa and the highest elongation rate of about 90%. Surprisingly, the 2:1 PCL/Gelatin sample also showed the best mesenchymal stem cell responses in terms of attachment, spreading, and cytoskeleton organization. Such correlation might be partly due to the fact that the enhanced mechanical property, an integral part of the physical microenvironment, likely played an important role in regulating the cellular functions. Overall, our results indicated that the PCL/Gelatin sample with the blend ratio of 2:1 was a superior candidate for scaffolds for tissue engineering applications.     

Gene expression by fibroblasts seeded on small intestinal submucosa and subjected to cyclic stretching

Extracellular matrix scaffolds derived from porcine small intestinal submucosa (SIS-ECM) have been shown to promote the formation of site-specific tissue in a number of preclinical animal studies. However, this constructive remodeling process requires that the scaffold be subjected to a site-specific mechanical environment. The specific quantitative effects of mechanical loading on the gene expression patterns of fibroblasts seeded on SIS-ECM are unknown and yet very important in the tissue remodeling process. The objective of the present study was to evaluate the expression of collagen type I (Col I), collagen type III (Col III), smooth muscle actin (SMA), tenascin-C (TN-C), matrix metalloprotease-2 (MMP-2), matrix metalloprotease-9 (MMP-9), transforming growth factor-beta1 (TGF-beta1), and transforming growth factor-beta3 (TGF-beta3) by fibroblasts subjected to various magnitudes (0%, 5%, 10%, and 15%) and frequencies (0.1 Hz, 0.3 Hz, and 0.5 Hz) of stretch. A new cyclic-stretching tissue culture (CSTC) system was developed. This system consists of eight independently controlled culture chambers that can be operated in a sterile incubator. Each chamber includes a load cell so that the load in each scaffold can be monitored. It was found that different stretching regimens led to complex and distinctive patterns of gene expression by fibroblasts seeded onto SIS-ECM. In general, the fibroblasts increased expression of Col I up to 5-fold and decreased that of Col III with increased frequency of stretch. In addition, the fibroblasts exhibited a contractile phenotype with increased expression of SMA, TN-C, and TGF-beta1. These findings support the concept that the mechanical environment of a remodeling ECM scaffold may have substantial effects on the behavior of cells within the scaffold and contribute to the site-specific tissue remodeling that has been observed in in vivo studies.     

Grafting of mesenchymal stem cell-seeded small intestinal submucosa to repair the deep partial-thickness burns

Purpose: Regenerative medicine provides many treatments for burn wounds, of which cell-seeded substitutes are encouraging for large and deep burns. To assess the feasibility of mesenchymal stem cell (MSC)-seeded small intestinal submucosa (SIS) to repair the deep partial-thickness burns, a rat study was performed. Materials & Methods: The burn model was created by contacting the dorsal surface directly with boiled water for 10 seconds. MSCs at passage 3 were seeded on the SIS before implantation. Three days after burn injury, the grafts were implanted onto the burn area. At 3, 7, 14 and 21 days post implantation, gross observation and histological assessments were performed. Results: SIS alone and MSC-seeded SIS were able to accelerate the burn wound closure by enhancing granulation tissue formation, increasing wound maturity, improving revascularization, and inducing the proliferation of neo-epidermal cells. Additionally, MSC-seeded SIS was much more effective than SIS alone for the repair of deep partial-thickness burns. Conclusion: Both SIS and MSC-seeded SIS were able to repair the large and deep burn wounds and the loaded MSCs possessed positive effects to accelerate the wound closure in a rat model.     

小肠黏膜下层在组织修复重建中的应用*

小肠黏膜下层是一种天然细胞外基质类材料,具有良好的生物相容性、机械性能以及低免疫原性等特点,植入宿主体内能促进细胞增殖和组织生长,在基础研究和临床工作中已被广泛用于泌尿系统、生殖系统、消化道、腱膜组织、心血管系统、皮肤等组织器官的修复重建,并且在板层角膜重建中具有广阔的应用前景。现就小肠黏膜下层的生物学特性、组织修复重建中的应用、存在的问题及未来的研究方向作一综述。     

The use of bi-layer silk fibroin scaffolds and small intestinal submucosa matrices to support bladder tissue regeneration in a rat model of spinal cord injury

Adverse side-effects associated with enterocystoplasty for neurogenic bladder reconstruction have spawned the need for the development of alternative graft substitutes. Bi-layer silk fibroin (SF) scaffolds and small intestinal submucosa (SIS) matrices were investigated for their ability to support bladder tissue regeneration and function in a rat model of spinal cord injury (SCI). Bladder augmentation was performed with each scaffold configuration in SCI animals for 10 wk of implantation and compared to non-augmented control groups (normal and SCI alone). Animals subjected to SCI alone exhibited a 72% survival rate (13/18) while SCI rats receiving SIS and bi-layer SF scaffolds displayed respective survival rates of 83% (10/12) and 75% (9/12) over the course of the study period. Histological (Masson's trichrome analysis) and immunohistochemical (IHC) evaluations demonstrated both implant groups supported de novo formation of smooth muscle layers with contractile protein expression [α-smooth muscle actin (α-SMA) and SM22α] as well as maturation of multi-layer urothelia expressing cytokeratin (CK) and uroplakin 3A proteins. Histomorphometric analysis revealed bi-layer SF and SIS scaffolds respectively reconstituted 64% and 56% of the level of α-SMA+ smooth muscle bundles present in SCI-alone controls, while similar degrees of CK+ urothelium across all experimental groups were detected. Parallel evaluations showed similar degrees of vascular area and synaptophysin+ boutons in all regenerated tissues compared to SCI-alone controls. In addition, improvements in certain urodynamic parameters in SCI animals, such as decreased peak intravesical pressure, following implantation with both matrix configurations were also observed. The data presented in this study detail the ability of acellular SIS and bi-layer SF scaffolds to support formation of innervated, vascularized smooth muscle and urothelial tissues in a neurogenic bladder model.     

猪小肠黏膜下层与兔骨髓间充质干细胞的体外复合培养

背景：小肠黏膜下层细胞外基质材料免疫原性低,具有良好生物相容性,是构建单一结构工程化组织的较好支架材料。 目的：观察体外兔骨髓间充质干细胞与猪小肠黏膜下层复合培养的生物相容性。 方法：采用密度梯度离心法结合贴壁法分离纯化培养兔骨髓间充质干细胞,在其接种前用红色免疫荧光标记,然后将第2代已标记的兔骨髓间充质干细胞接种在猪小肠黏膜下层上。 结果与结论：①组织学观察：骨髓间充质干细胞与小肠黏膜下层上复合培养1周时细胞呈单层生长,荧光显微镜下观察标记的骨髓间充质干细胞显示均匀红色荧光,复合培养2周细胞呈多层生长,并显示更密集的红色荧光。②扫描电镜观察：复合培养2 d,骨髓间充质干细胞黏附于材料表面并伸展;复合培养1周,小肠黏膜下层被骨髓间充质干细胞分泌的胶原覆盖;2周后细胞在材料上已大量增殖形成融合,细胞连接紧密,细胞分泌大量基质,并分层。表明小肠黏膜下层与骨髓间充质干细胞具有良好的相容性。