Gelatin/PLLA Sponge-Like Scaffolds Allow Proliferation and Osteogenic Differentiation of Human Mesenchymal Stromal Cells

Treatment of Optic Canal Decompression Combined with Umbilical Cord Mesenchymal Stem (Stromal) Cells for Indirect Traumatic Optic Neuropathy: A Phase 1 Clinical Trial

PURPOSE

This study was aimed to investigate the safety and feasibility of umbilical cord-derived mesenchymal stem cell (MSC) transplantation in patients with traumatic optic neuropathy (TON).

METHODS

This is a single-center, prospective, open-labeled phase 1 study that enrolled 20 patients with TON. Patients consecutively underwent either optic canal decompression combined with MSC local implantation treatment (group 1) or only optic canal decompression (group 2). Patients were evaluated on the first day, seventh day, first month, third month, and sixth month postoperatively. Adverse events, such as fever, urticarial lesions, nasal infection, and death, were recorded at each visit. The primary outcome was changes in best-corrected visual acuity. The secondary outcomes were changes in color vision, relative afferent pupillary defect, and flash visual evoked potential.

RESULTS

All 20 patients completed the 6-month follow-up. None of them had any systemic or ocular complications. The change in best-corrected visual acuity at follow-up was not significantly different between group 1 and group 2 (p > 0.05); however, group 1 showed better visual outcome than group 2. Both groups showed significant improvements in vision compared with the baseline (p < 0.05); however, there were no statistically significant differences between the groups (p > 0.05). In addition, no adverse events related to local transplantation were observed in the patients.

CONCLUSIONS

A single, local MSC transplantation in the optic nerve is safe for patients with TON.

Proposal of a Novel Natural Biomaterial, the Scleral Ossicle, for the Development of Vascularized Bone Tissue In Vitro

Recovering of significant skeletal defects could be partially abortive due to the perturbations that affect the regenerative process when defects reach a critical size, thus resulting in a non-healed bone. The current standard treatments include allografting, autografting, and other bone implant techniques. However, although they are commonly used in orthopedic surgery, these treatments have some limitations concerning their costs and their side effects such as potential infections or malunions. On this account, the need for suitable constructs to fill the gap in wide fractures is still urgent. As an innovative solution, scleral ossicles (SOs) can be put forward as natural scaffolds for bone repair. SOs are peculiar bony plates forming a ring at the scleral-corneal border of the eyeball of lower vertebrates. In the preliminary phases of the study, these ossicles were structurally and functionally characterized. The morphological characterization was performed by SEM analysis, MicroCT analysis and optical profilometry. Then, UV sterilization was carried out to obtain a clean support, without neither contaminations nor modifications of the bone architecture. Subsequently, the SO biocompatibility was tested in culture with different cell lines, focusing the attention to the differentiation capability of endothelial and osteoblastic cells on the SO surface. The results obtained by the above mentioned analysis strongly suggest that SOs can be used as bio-scaffolds for functionalization processes, useful in regenerative medicine.

Osteogenic differentiation of mesenchymal stem cells cultured on PLLA scaffold coated with Wharton's Jelly

Poly-L-lactic acid (PLLA) electrospun nanofiber scaffold is one of the most commonly used synthetic polymer scaffolds for bone tissue engineering application. However, PLLA is hydrophobic in nature, hence does not maintain proper cell adhesion and tissue formation, moreover, it cannot provide the osteo-inductive environment due to inappropriate surface characteristic and the lack of surface motives participating in the first cellular events. To modify these shortcomings different approaches have been used, among those the most commonly used one is coating of the surface of the electrospun nanofiber with natural materials. In this work Wharton's jelly (WJ), a tissue which surrounds the umbilical cord vessels, reaches in high amounts of extracellular matrix (ECM) components mainly; collagen, hyaluronic acid and several sulphated glycosaminoglycans (GAGs) were used to cover the surface of electrospun PLLA nanofiber scaffolds. The surface morphology of the nanofiber scaffold was evaluated via scanning electron microscope, and the in vitro osteogenic differentiation potential was determined by MTT assay and common osteogenic marker tests such as alkaline phosphatase (ALP) activity and calcium deposition tests. Coating of WJ could not change the surface morphology and diameter of the nanofibers. However, WJ-PLLA scaffolds showed higher proliferation of human mesenchymal stem cells (MSC) than tissue culture plate (TCP) and pristine PLLA scaffolds, moreover, WJ-PPLA scaffold demonstrated significant alkaline phosphatase activity and calcium mineralization than either TCP or PLLA nanofiber scaffolds.

Regulation of adipose-tissue-derived stromal cell orientation and motility in 2D- and 3D-cultures by direct-current electrical field

Cell alignment and motility play a critical role in a variety of cell behaviors, including cytoskeleton reorganization, membrane-protein relocation, nuclear gene expression, and extracellular matrix remodeling. Direct current electric field (EF) in vitro can direct many types of cells to align vertically to EF vector. In this work, we investigated the effects of EF stimulation on rat adipose-tissue-derived stromal cells (ADSCs) in 2D-culture on plastic culture dishes and in 3D-culture on various scaffold materials, including collagen hydrogels, chitosan hydrogels and poly(L-lactic acid)/gelatin electrospinning fibers. Rat ADSCs were exposed to various physiological-strength EFs in a homemade EF-bioreactor. Changes of morphology and movements of cells affected by applied EFs were evaluated by time-lapse microphotography, and cell survival rates and intracellular calcium oscillations were also detected. Results showed that EF facilitated ADSC morphological changes, under 6 V/cm EF strength, and that ADSCs in 2D-culture aligned vertically to EF vector and kept a good cell survival rate. In 3D-culture, cell galvanotaxis responses were subject to the synergistic effect of applied EF and scaffold materials. Fast cell movement and intracellular calcium activities were observed in the cells of 3D-culture. We believe our research will provide some experimental references for the future study in cell galvanotaxis behaviors.

Graft of a tissue-engineered neural scaffold serves as a promising strategy to restore myelination after rat spinal cord transection

Remyelination remains a challenging issue in spinal cord injury (SCI). In the present study, we cocultured Schwann cells (SCs) and neural stem cells (NSCs) with overexpression of neurotrophin-3 (NT-3) and its high affinity receptor tyrosine kinase receptor type 3 (TrkC), respectively, in a gelatin sponge (GS) scaffold. This was aimed to generate a tissue-engineered neural scaffold and to investigate whether it could enhance myelination after a complete T10 spinal cord transection in adult rats. Indeed, many NT-3 overexpressing SCs (NT-3-SCs) in the GS scaffold assumed the formation of myelin. More strikingly, a higher incidence of NSCs overexpressing TrkC differentiating toward myelinating cells was induced by NT-3-SCs. By transmission electron microscopy, the myelin sheath showed distinct multilayered lamellae formed by the seeded cells. Eighth week after the scaffold was transplanted, some myelin basic protein (MBP)-positive processes were observed within the transplantation area. Remarkably, certain segments of myelin derived from NSC-derived myelinating cells and NT-3-SCs were found to ensheath axons. In conclusion, we show here that transplantation of the GS scaffold promotes exogenous NSC-derived myelinating cells and SCs to form myelins in the injury/transplantation area of spinal cord. These findings thus provide a neurohistological basis for the future application or transplantation using GS neural scaffold to repair SCI.

Growing bone tissue-engineered niches with graded osteogenicity: an in vitro method for biomimetic construct assembly

The traditional bone tissue-engineering approach exploits mesenchymal stem cells (MSCs) to be seeded once only on three-dimensional (3D) scaffolds, hence, differentiated for a certain period of time and resulting in a homogeneous osteoblast population at the endpoint. However, after achieving terminal osteodifferentiation, cell viability is usually markedly compromised. On the other hand, naturally occurring osteogenesis results from the coexistence of MSC progenies at distinct differentiative stages in the same microenvironment. This diversification also enables long-term viability of the mature tissue. We report an easy and tunable in vitro method to engineer simple osteogenic cell niches in a biomimetic fashion. The niches were grown via periodic reseeding of undifferentiated MSCs on MSC/scaffold constructs, the latter undergoing osteogenic commitment. Time-fractioning of the seeded cell number during differentiation time of the constructs allowed graded osteogenic cell populations to be grown together on the same scaffolds (i.e., not only terminally differentiated osteoblasts). In such cell-dynamic systems, the overall differentiative stage of the constructs could also be tuned by varying the cell density seeded at each inoculation. In this way, we generated two different biomimetic niche models able to host good reservoirs of preosteoblasts and other osteoprogenitors after 21 culture days. At that time, the niche type resulting in 40.8% of immature osteogenic progenies and only 59.2% of mature osteoblasts showed a calcium content comparable to the constructs obtained with the traditional culture method (i.e., 100.03 ± 29.30 vs. 78.51 ± 28.50 pg/cell, respectively; p=not significant), the latter colonized only by fully differentiated osteoblasts showing exhausted viability. This assembly method for tissue-engineered constructs enabled a set of important parameters, such as viability, colonization, and osteogenic yield of the MSCs to be balanced on 3D scaffolds, thus achieving biomimetic in vitro models with graded osteogenicity, which are more complex and reliable than those currently used by tissue engineers.

Differentiation of human mesenchymal stem cell spheroids under microgravity conditions

To develop and characterize a novel cell culture method for the generation of undifferentiated and differentiated human mesenchymal stem cell 3D structures, we utilized the RWV system with a gelatin-based scaffold. 3 × 10(6) cells generated homogeneous spheroids and maximum spheroid loading was accomplished after 3 days of culture. Spheroids cultured in undifferentiated spheroids of 3 and 10 days retained expression of CD44, without expression of differentiation markers. Spheroids cultured in adipogenic and osteogenic differentiation media exhibited oil red O staining and von Kossa staining, respectively. Further characterization of osteogenic lineage, showed that 10 day spheroids exhibited stronger calcification than any other experimental group corresponding with significant expression of vitamin D receptor, alkaline phosphatase, and ERp60 . In conclusion this study describes a novel RWV culture method that allowed efficacious engineering of undifferentiated human mesenchymal stem cell spheroids and rapid osteogenic differentiation. The use of gelatin scaffolds holds promise to design implantable stem cell tissue of various sizes and shapes for future regenerative treatment.

Rat bone marrow stromal cells-seeded porous gelatin/tricalcium phosphate/oligomeric proanthocyanidins composite scaffold for bone repair

Repair of bone defects remains a major challenge in orthopaedic surgery. Bone tissue engineering is an attractive approach for treating bone loss in various shapes and amounts. The aim of this study was to prepare and evaluate the feasibility of a porous scaffold, which was composed of oligomeric proanthocyanidin crosslinked gelatin mixed with β-tricalcium phosphate (GTP) and was seeded with bone marrow stromal cells (BMSCs) as a bone substitute. GTP scaffolds were made porous using a salt-leaching method. The physicochemical properties of the scaffold were evaluated to determine the optimal salt:composite weight ratio. The results indicated that the GTP scaffold had a favourable macroporous structure and higher porosity when the salt:composite weight ratio was 4:1. Cytotoxic tests demonstrated that extracts from the GTP scaffolds promoted the proliferation of BMSCs. Rat BMSCs were seeded on a GTP scaffold and cultured in a spinner flask. After 2 weeks of culture, scanning electron microscopy observation showed that the cells adhered well to the surfaces of the pores in the scaffold. Moreover, this study explored the biological response of rat calvarial bone to the scaffold to evaluate its potential in bone tissue engineering. Bone defects were filled with BMSC-seeded GTP scaffold and acellular GTP scaffold. After 8 weeks, the scaffold induced new bone formation at a bone defect, as was confirmed by X-ray microradiography and histology. The BMSC-seeded scaffold induced more new bone formation than did an acellular scaffold. These observations suggest that the BMSCs-seeded GTP scaffold can promote the regeneration of defective bone tissue.

Influence of porcine intervertebral disc matrix on stem cell differentiation

For back disorders, cell therapy is one approach for a real regeneration of a degenerated nucleus pulposus. Human mesenchymal stem cells (hMSC) could be differentiated into nucleus pulposus (NP)-like cells and used for cell therapy. Therefore it is necessary to find a suitable biocompatible matrix, which supports differentiation. It could be shown that a differentiation of hMSC in a microbial transglutaminase cross-linked gelatin matrix is possible, but resulted in a more chondrocyte-like cell type. The addition of porcine NP extract to the gelatin matrix caused a differentiation closer to the desired NP cell phenotype. This concludes that a hydrogel containing NP extract without any other supplements could be suitable for differentiation of hMSCs into NP cells. The NP extract itself can be cross-linked by transglutaminase to build a hydrogel free of NP atypical substrates. As shown by side-specific biotinylation, the NP extract contains molecules with free glutamine and lysine residues available for the transglutaminase.

Bone marrow mesenchymal stem cells in a three-dimensional gelatin sponge scaffold attenuate inflammation, promote angiogenesis, and reduce cavity formation in experimental spinal cord injury

Three-dimensional (3D) gelatin sponge (GS) scaffolds were constructed by ensheathing GS with a thin film of poly-(lactide-co-glycolide) (PLGA). Rat bone marrow-derived mesenchymal stem cells (MSCs) were isolated, cultured, and then seeded to the scaffolds. Distribution of cells and cell growth, survival, and proliferation within the scaffolds were then determined. Immunofluorescence and Western blot analysis were employed to detect the deposition of fibronectin to the scaffolds on day 3 and day 7 of culture. Scaffolds with or without MSCs were then transplanted into the transected rat spinal cord. One or 8 weeks following transplantation, cavity areas, activated macrophages/microglia, expression of TNF-α and IL-1β, and neovascularization within the grafts were examined and quantified. Deposition of fibronectin (FN) and expression of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1α (HIF-1α) as potential inducing factors for angiogenesis were also examined. Results showed that 3D GS scaffolds allowed MSCs to adhere, survive, and proliferate and also FN to deposit. In vivo transplantation experiments demonstrated that these scaffolds were biocompatible, and MSCs seeded to the scaffolds played an important role in attenuating inflammation, promoting angiogenesis, and reducing cavity formation. Therefore, the GS scaffolds with MSCs may serve as promising supporting transplants for repairing spinal cord injury.

Synergistic effect of polyelectrolyte multilayers and osteogenic growth medium on differentiation of human mesenchymal stem cells

Layer-by-layer assembly of biogenic polyelectrolytes (PEL) was carried out on the surface of poly (L-lactide) to generate polyelectrolyte multilayers (PEM) that foster osteogenic differentiation of human mesenchymal stem cell (hMSC). Gelatin (GEL), hyaluronic acid (HA) and heparin (HEP) were chosen as polyanions, while chitosan (CHI) was employed as polycation. Multilayer formation was monitored by surface plasmon resonance and water contact angle measurements showing that layer formation process and surface wetting properties depended on the type of polyanions. While HEP as strong PEL led to thicker and more hydrophilic PEM, layer mass was lower for weak polyanions GEL and HA. Short-term adhesion studies with hMSC showed strong adhesion and spreading of cells on PEM composed of GEL/CHI and low spreading, motile phenotype and aggregation of hMSC on HEP/CHI or HA/CHI. Long term studies over three weeks were carried out to follow growth and differentiation of hMSC on the PEM. Weak osteogenic differentiation of hMSC was observed on GEL/CHI if cells were cultured in normal medium while no osteogenic phenotypes were observed on HEP/CHI or HA/CHI. When cells were cultured in osteogenic differentiation medium, however, PEM composed of HEP/CHI or HA/CHI promoted differentiation of hMSC towards osteoblasts, while PEM composed of GEL/CHI failed to do so. Overall, the composition of PEMs can be used as additional tool to control osteogenic differentiation of hMSC.