Metacarpophalangeal collateral ligament reconstruction using small intestinal submucosa in an equine model

An intestinal model with a finger-like villus structure fabricated using a bioprinting process and collagen/SIS-based cell-laden bioink

The surface of the small intestine has a finger-like microscale villus structure, which provides a large surface area to realize efficient digestion and absorption. However, the fabrication of a villus structure using a cell-laden bioink containing a decellularized small intestine submucosa, SIS, which can induce significant cellular activities, has not been attempted owing to the limited mechanical stiffness, which sustains the complex projective finger-like 3D structure. In this work, we developed a human intestinal villi model with an innovative bioprinting process using a collagen/SIS cell-laden bioink. Methods: A Caco-2-laden microscale villus structure (geometry of the villus: height = 831.1 ± 36.2 μm and diameter = 190.9 ± 3.9 μm) using a bioink consisting of collagen type-I and SIS was generated using a vertically moving 3D bioprinting process. By manipulating various compositions of dECM and a crosslinking agent in the bioink and the processing factors (printing speed, printing time, and pneumatic pressure), the villus structure was achieved. Results: The epithelial cell-laden collagen/SIS villi showed significant cell proliferation (1.2-fold) and demonstrated meaningful results for the various cellular activities, such as the expression of tight-junction proteins (ZO-1 and E-cadherin), ALP and ANPEP activities, MUC17 expression, and the permeability coefficient and the glucose uptake ability, compared with the pure 3D collagen villus structure. Conclusion: In vitro cellular activities demonstrated that the proposed cell-laden collagen/dECM villus structure generates a more meaningful epithelium layer mimicking the intestinal structure, compared with the pure cell-laden collagen villus structure having a similar villus geometry. Based on the results, we believe that this dECM-based 3D villus model will be helpful in obtaining a more realistic physiological small-intestine model.

Applications of decellularized materials in tissue engineering: advantages, drawbacks and current improvements, and future perspectives

Decellularized materials (DMs) are attracting more and more attention in tissue engineering because of their many unique advantages, and they could be further improved in some aspects through various means.

Small intestinal submucosa: superiority, limitations and solutions, and its potential to address bottlenecks in tissue repair

Small intestinal submucosa (SIS) has attracted much attention in tissue repair because it can provide plentiful bioactive factors and a biomimetic three-dimensional microenvironment to induce desired cellular functions.

A Contact-Based Method for Differentiation of Human Mesenchymal Stem Cells into an Endothelial Cell-Phenotype

Adult stem cells such as mesenchymal stem cells (MSC) are known to possess the ability to augment neovascularization processes and are thus widely popular as an autologous source of progenitor cells. However there is a huge gap in our current knowledge of mechanisms involved in differentiating MSC into endothelial cells (EC), essential for lining engineered blood vessels. To fill up this gap, we attempted to differentiate human MSC into EC, by culturing the former onto chemically fixed layers of EC or its ECM, respectively. We expected direct contact of MSC when cultured atop fixed EC or its ECM, would coax the former to differentiate into EC. Results showed that human MSC cultured atop chemically fixed EC or its ECM using EC-medium showed enhanced expression of CD31, a marker for EC, compared to other cases. Further in all human MSC cultured using EC-medium, typically characteristic cobble stone shaped morphologies were noted in comparison to cells cultured using MSC medium, implying that the differentiated cells were sensitive to soluble VEGF supplementation present in the EC-medium. Results will enhance and affect therapies utilizing autologous MSC as a cell source for generating vascular cells to be used in a variety of tissue engineering applications.

An injectable nucleus pulposus cell-modified decellularized scaffold: biocompatible material for prevention of disc degeneration

We developed a nucleus pulposus cell (NPC)-modulated decellularized small intestinal submucosa (SIS) scaffold, and assessed the ability of this material to prevent Intervertebral disc degeneration (IVD) degeneration. Decellularized porcine SIS was squashed into particles and the biological safety and efficiency of these particles were evaluated. Next, SIS particles were seeded with rabbit NPCs, cultured for two months in vitro, decellularized again and suspended for intervertebral injection. We demonstrated that use of the decellularization protocol resulted in the removal of cellular components with maximal retention of extracellular matrix. The xenogeneic decellularized SIS did not display cytotoxicity in vitro and its application prevented NPC degradation. Furthermore, the xenogeneic SIS microparticles were effective in preventing IVD progression in vivo in a rabbit disc degeneration model. In conclusion, our study describes an optimized method for decellularized SIS preparation and demonstrated that the material is safe and effective for treating IVD degeneration.

Reprint of: Extracellular matrix as a biological scaffold material: Structure and function

Biological scaffold materials derived from the extracellular matrix (ECM) of intact mammalian tissues have been successfully used in a variety of tissue engineering/regenerative medicine applications both in preclinical studies and in clinical applications. Although it is recognized that the materials have constructive remodeling properties, the mechanisms by which functional tissue restoration is achieved are not well understood. There is evidence to support essential roles for both the structural and functional characteristics of the biological scaffold materials. This paper provides an overview of the composition and structure of selected ECM scaffold materials, the effects of manufacturing methods upon the structural properties and resulting mechanical behavior of the scaffold materials, and the in vivo degradation and remodeling of ECM scaffolds with an emphasis on tissue function.

Small intestinal submucosa segments as matrix for tissue engineering: review

Tissue engineering (TE) is an emerging interdisciplinary field aiming at the restoration or improvement of impaired tissue function. A combination of cells, scaffold materials, engineering methods, and biochemical and physiological factors is employed to generate the desired tissue substitute. Scaffolds often play a pivotal role in the engineering process supporting a three-dimensional tissue formation. The ideal scaffold should mimic the native extracellular environment providing mechanical and biological properties to allow cell attachment, migration, and differentiation, as well as remodeling by the host organism. The scaffold should be nonimmunogenic and should ideally be resorbed by the host over time, leaving behind only the regenerated tissue. More than 40 years ago, a preparation of the small intestine was introduced for the replacement of vascular structures. Since then the small intestinal submucosa (SIS) has gained a lot of interest in TE and subsequent clinical applications, as this material exhibits key features of a highly supportive scaffold. This review will focus on the general properties of the SIS and its applications in therapeutical approaches as well as in generating tissue substitutes in vitro. Furthermore, the main problem of TE, which is the insufficient nourishment of cells within three-dimensional, artificial tissues exceeding certain dimensions is addressed. To solve this issue the implementation of another small intestine-derived preparation, the biological vascularized matrix (BioVaM), could be a feasible option. The BioVaM comprises in addition to SIS the arterial and venous mesenteric pedicles and exhibits thereby a perfusable vessel bed that is preserved after decellularization.

Effects of athletic conditioning on horses with degenerative suspensory ligament desmitis: a preliminary report

Equine degenerative suspensory ligament desmitis (DSLD) is a debilitating condition that has limited response to rest and stall confinement. This study was designed to test the hypothesis that mild to moderate DSLD is not worsened by consistent exercise. Paso Fino and Peruvian Paso horses (two normal horses and four horses with DSLD) were exercised for 30 min every other day for 8 weeks and then pasture rested for 4 months. Gait analysis, radiographs, ultrasound and serum insulin and glucose concentrations were performed prior to the exercise trial and at each time point. Vertical impulse increased after 8 weeks of exercise and 4 months of pasture rest in DSLD-affected horses. Suspensory ligament fiber pattern subjectively improved with exercise in affected horses. Insulin levels significantly decreased from baseline in all horses after 4 and 8 weeks of exercise. Exercise did not seem to exacerbate and may have improved signs of DSLD in mild to moderate cases.

Radiofrequency energy on cortical bone and soft tissue: a pilot study

BACKGROUND

Radiofrequency-generating energy devices have been used clinically in musculoskeletal procedures to provide hemostasis and capsular shrinkage (thermal capsulorrhaphy). However, the dose-effects are not well known.

QUESTIONS/PURPOSES

We therefore determined dosage effects of radiofrequency energy on bone, skin incisions, and joint capsule in sheep.

METHODS

Five mature sheep had six 2.5-cm(2) tibial periosteal defects and six 1.0-cm skin incisions assigned to six treatments varying by watts and fluence (f = watts . seconds/cm(2)): (1) untreated control, (2) 50 W for 9.5 seconds (190f; n = 5), (3) 110 W for 4.3 seconds (190f; n = 5), (4) 170 W for 2.8 seconds (190f; n = 5), (5) 170 W for 5.6 seconds (380f; n = 5), or (6) 170 W for 8.4 seconds (570f; n = 5). Outcomes included hemostasis, contraction, healing, and histomorphometry for inflammation and necrosis at 2 weeks.

RESULTS

Radiofrequency energy application on skin at 190f or greater had more than 80% hemostasis and dose-dependent contraction, inflammation, and necrosis. Radiofrequency energy application on bone had good (70%) hemostasis at 190f and complete (> 95%) hemostasis at 380f and 570f, without histologic or clinically detectable necrosis.

CONCLUSIONS

Hemostasis can be achieved with radiofrequency energy at 190f in skin and bone. Bone necrosis was not detected at up to 570f. Using fluence greater than 190f in skin achieved dose-dependent necrosis and incisional contraction.

CLINICAL RELEVANCE

Radiofrequency energy can be used on bone and skin for hemostasis, but potential incisional complications, such as necrosis and an atypical firm and desiccated surface, should be expected.

Small intestinal submucosa for anular defect closure: long-term response in an in vivo sheep model

STUDY DESIGN

After undergoing anulotomy, lumbar intervertebral discs from sheep were treated with small intestinal submucosa (SIS) and assessed functionally at 24 weeks after surgery.

OBJECTIVE

To determine the efficacy of an SIS-based patch and plug scaffold to facilitate anular defect closure and anular functional recovery after anulotomy and partial discectomy.

SUMMARY OF BACKGROUND DATA

The incidence of reherniation following discectomy remains high and mechanical means of anular closure have met with limited success. SIS is a naturally occurring collagen-based material, which acts as a resorbable scaffold in vivo that promotes soft tissue regeneration.

METHODS

Twelve sheep underwent retroperitoneal exposure of the lumbar spine. Three levels were assigned to either: no additional procedure, box anulotomy alone, or box anulotomy followed by placement of an SIS "patch and plug" anchored by titanium bone screws. At 26 weeks after surgery, 18 motion segments underwent pressure-volume testing to assess the competency of the anulus. High resolution MRI images were taken of the remaining 18 segments. Undecalcified histology was conducted on all specimens.

RESULTS

Radiographs, MRI images, and histology indicate that there was an exuberant tissue response at SIS-treated levels. New tissue formation in SIS-treated specimens was integrated well with the native anulus, but did not resemble the organization of native anulus. The extent of anular closure was substantial enough to allow the disc a functional recovery to a mean 66% of its capacity to develop internal pressure. MRI images indicate that SIS-treated levels did not maintain signal intensity comparable to exposure-only (intact) levels, but SIS-treated discs were statistically significantly higher than anulotomy-only levels.

CONCLUSION

SIS-treated discs were better able to maintain hydration and resulted in a functional recovery relative to anulotomy alone levels. The SIS patch and plug reduced the cascade of functional degeneration that an intervertebral disc undergoes following anulotomy.