Expansion and Delivery of Adipose-Derived Mesenchymal Stem Cells on Three Microcarriers for Soft Tissue Regeneration

Composite Microparticles of Fat Graft and GFR Matrigel Improved Volume Retention by Promoting Cell Migration and Vessel Regeneration

BACKGROUND

The retention volume of autologous fat grafts decreases after transplantation due to limited nutrition infiltration and insufficient blood supply. Structural fat grafts and the 3M (multipoint, multitunnel, and multilayer) injection technique have been considered to improve the survival of grafts; however, it is difficult for surgeons to practice in the clinic because grafts tend to gather into a cluster, especially in large volume fat grafting. Therefore, we hypothesize that prefabricated microparticle fat grafts (PFMG) may improve the retention rate.

METHODS

The C57BL/6 mouse fat particles were embedded in growth factor-reduced (GFR)-Matrigel to detect cell migration by immunofluorescence staining in vitro. PFMG was prepared by mixing mouse fat particles and GFR Matrigel in a 1:1 volume ratio and injected subcutaneously into C57BL/6 mice. Fat particles mixed with PBS in equal volume served as control group. The grafts were harvested at 1, 4, 8, and 12 weeks after sacrifice. The retention rate of grafts at each time point was measured, and the structural alterations were detected by SEM. Fat necrosis and blood vessel density were evaluated by histological analysis.

RESULTS

CD34+ cells are migrated from the PFMG and formed a tree-like tubular network in the in vitro study. The retention rate was higher in the PFMG group than in the control group at week 12 (38% vs. 30%, p < 0.05). After transplantation, the dissociated structure of fat particles was maintained in PFMG by SEM analysis. Histological analysis of PFMG confirmed less fat necrosis and more blood vessel density in the PFMG group at the early stage than in the control group. The GFR Matrigel was displaced by adipose tissue with time.

CONCLUSIONS

In this study, we developed a novel fat grafting method, PFMG that dispersed fat grafts and maintained the structure after transplantation. High volume retention volume of PFMG was achieved by promoting cell migration and vessel regeneration.

NO LEVEL ASSIGNED

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The Posthyaluronidase Syndrome: Dosing Strategies for Hyaluronidase in the Dissolving of Facial Filler and Independent Predictors of Poor Outcomes

Background

Hyaluronic acid dermal fillers are used extensively in periocular aesthetic medicine, and the incidence of filler-related complications is increasing. This study aimed to investigate the optimal dosing strategy for hyaluronidase and to identify predictors of poor outcomes.

Methods

We performed a retrospective review of 157 orbits of 90 patients treated with hyaluronidase over a 4-year period. Demographic data, indication, and details of hyaluronidase treatment and outcomes were recorded.

Results

The primary indication for dissolving filler was swelling in 52%, lumpiness in 20%, and before surgical blepharoplasty in 17%. The most frequently used hyaluronidase concentration was 150 U per mL in 66%, followed by 75 U per mL in 31%, 37.5 U per mL in 3%, and 100 U per mL in 1%. Outcomes were characterized as follows: 59% with a satisfactory result; 24% as insufficient treatment requiring further hyaluronidase; and 18% complaining of facial changes such as hollowing, indicating a post hyaluronidase syndrome. There was no statistical difference in outcomes between the 75 and 150 U per mL dosage groups (P = 0.625). A significant correlation was identified between posthyaluronidase syndrome and duration of filler in situ (P = 0.00019) and volume of filler (P = 0.000017).

Conclusions

The posthyaluronidase syndrome may be related to previous filler volume and duration, rather than the concentration or dose of hyaluronidase used. All patients should be informed about the risks of adverse effects after hyaluronidase treatment; patients with longer histories of filler use and higher total volumes should be advised of the increased risk.

Biomaterials combined with ADSCs for bone tissue engineering: current advances and applications

In recent decades, bone tissue engineering, which is supported by scaffold, seed cells and bioactive molecules (BMs), has provided new hope and direction for treating bone defects. In terms of seed cells, compared to bone marrow mesenchymal stem cells, which were widely utilized in previous years, adipose-derived stem cells (ADSCs) are becoming increasingly favored by researchers due to their abundant sources, easy availability and multi-differentiation potentials. However, there is no systematic theoretical basis for selecting appropriate biomaterials loaded with ADSCs. In this review, the regulatory effects of various biomaterials on the behavior of ADSCs are summarized from four perspectives, including biocompatibility, inflammation regulation, angiogenesis and osteogenesis, to illustrate the potential of combining various materials with ADSCs for the treatment of bone defects. In addition, we conclude the influence of additional application of various BMs on the bone repair effect of ADSCs, in order to provide more evidences and support for the selection or preparation of suitable biomaterials and BMs to work with ADSCs. More importantly, the associated clinical case reports and experiments are generalized to provide additional ideas for the clinical transformation and application of bone tissue engineering loaded with ADSCs.

Recent advances in decellularized biomaterials for wound healing

The skin is one of the most essential organs in the human body, interacting with the external environment and shielding the body from diseases and excessive water loss. Thus, the loss of the integrity of large portions of the skin due to injury and illness may lead to significant disabilities and even death. Decellularized biomaterials derived from the extracellular matrix of tissues and organs are natural biomaterials with large quantities of bioactive macromolecules and peptides, which possess excellent physical structures and sophisticated biomolecules, and thus, promote wound healing and skin regeneration. Here, we highlighted the applications of decellularized materials in wound repair. First, the wound-healing process was reviewed. Second, we elucidated the mechanisms of several extracellular matrix constitutes in facilitating wound healing. Third, the major categories of decellularized materials in the treatment of cutaneous wounds in numerous preclinical models and over decades of clinical practice were elaborated. Finally, we discussed the current hurdles in the field and anticipated the future challenges and novel avenues for research on decellularized biomaterials-based wound treatment.

TiO2/HA and Titanate/HA Double-Layer Coatings on Ti6Al4V Surface and Their Influence on In Vitro Cell Growth and Osteogenic Potential

Hydroxyapatite (HA) layers are appropriate biomaterials for use in the modification of the surface of implants produced inter alia from a Ti6Al4V alloy. The issue that must be solved is to provide implants with appropriate biointegration properties, enabling the permanent link between them and bone tissues, which is not so easy with the HA layer. Our proposition is the use of the intermediate layer ((IL) = TiO₂, and titanate layers) to successfully link the HA coating to a metal substrate (Ti6Al4V). The morphology, structure, and chemical composition of Ti6Al4V/IL/HA systems were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectrometry (EDS). We evaluated the apatite-forming ability on the surface of the layer in simulated body fluid. We investigated the effects of the obtained systems on the viability and growth of human MG-63 osteoblast-like cells, mouse L929 fibroblasts, and adipose-derived human mesenchymal stem cells (ADSCs) in vitro, as well as on their osteogenic properties. Based on the obtained results, we can conclude that both investigated systems reflect the physiological environment of bone tissue and create a biocompatible surface supporting cell growth. However, the nanoporous TiO₂ intermediate layer with osteogenesis-supportive activity seems most promising for the practical application of Ti6Al4V/TiO₂/HA as a system of bone tissue regeneration.

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.

Advances of adipose-derived mesenchymal stem cells-based biomaterial scaffolds for oral and maxillofacial tissue engineering

The management of oral and maxillofacial tissue defects caused by tumors, trauma, and congenital or acquired deformities has been a major challenge for surgeons over the last few decades. Autologous tissue transplantation, the gold standard of tissue reconstruction, is a valid method for repairing the oral and maxillofacial functions and aesthetics. However, several limitations hinder its clinical applications including complications of donor sites, limited tissue volume, and uncertain long-term outcomes. Adipose-derived mesenchymal stem cells (ADMSCs) widely exist in adipose tissue and can be easily obtained through liposuction. Like the bone marrow-derived mesenchymal stem cells (BMSCs), ADMSCs also have the multi-pluripotent potencies to differentiate into osteoblasts, chondrocytes, neurons, and myocytes. Therefore, the multilineage capacity of ADMSCs makes them valuable for cell-based medical therapies. In recent years, researchers have developed many candidates of ADMSCs-based biomaterial scaffolds to cater for the needs of oral and maxillofacial tissue engineering due to their superior performance. This review presents the advances and applications of ADMSCs-based biomaterial scaffolds, and explores their tissue engineering prospects in oral and maxillofacial reconstructions.

Altered properties of human adipose-derived mesenchymal stromal cell during continuous in vitro cultivation

Adipose-derived stromal cells (ASCs) are now recognized as an accessible, abundant, and reliable stem cells for tissue engineering and regenerative medicine. However, ASCs should be expanded long term in order to harvest higher cell number for clinical application. In this study, ASCs isolated from human subcutaneous adipose tissue and senescence after long-term expansion was evaluated. The results showed that following in vitro expansion to the 15th passage, ASCs show changes in morphology (toward the "fried egg" morphology) and decrease in proliferation potential. Nonetheless, ASCs maintained differentiation potential toward osteoblasts, chondrocytes, and adipocytes. The senescent ASCs show impaired migration capacity under the same basal conditions. OXPHOS and glycolysis decreased slightly in culture from passage 5 to passage 15. ASCs also showed increased accumulation of beta-galactosidase in culture. Expression of senescence markers p53, p16, and p21 were also increased accompanied with the increase of passages. Experiment data showed that ASCs biological characteristics depended and changed with age. We recommend the use of early-passage cells, particularly those before passage 5, for efficacious therapeutic application of stem cells.

Tissue Engineering Microtissue: Construction, Optimization, and Application

Until now, there is no clear definition of microtissue; it usually refers to the microtissue formed by the aggregation of seed cells under the action of cell-cell or cell-extracellular matrix (ECM). Compared with traditional cell monolayer culture, cells are cultivated into a three-dimensional microstructure in a specific way. The microstructure characteristics of microtissue are similar to natural tissues and can promote cell proliferation and differentiation. Therefore, it has a broader range of biomedical applications in tissue engineering. The traditional tissue engineering strategy is to add high-density seed cells and biomolecules on a preformed scaffold to construct a tissue engineering graft. However, due to the destruction of the ECM of the cells cultured in a monolayer during the digestion process with trypsin, the uneven distribution of the cells in the scaffold, and the damage of various adverse factors after the cells are implanted in the scaffold, this strategy is often ineffective, and the subsequent applications still face challenges. This article reviews the latest researches of a new strategy-tissue engineering microtissue strategy; discuss several traditional construction methods, structure, and function optimization; and practical application of microtissue. The review aims to provide a reference for future research on tissue engineering microtissue. Impact statement The traditional tissue engineering strategies have several disadvantages, researchers have conducted extensive research on tissue engineering microtissues in recent years, and they make significant progress. Microtissue is a kind of microtissue with three-dimensional structure, its microstructure is similar to that of natural tissue. In addition, microtissue implantation can protect cells from mechanical interference, inflammation, and other adverse factors. Furthermore, it improves the survival rate of cells and the therapeutic effect of tissue-engineered grafts. However, the practical conditions, advantages, and disadvantages of tissue engineering microtissue have not been fully elucidated. The purpose of this review is to discuss the latest research progress of microtissue and provide a reference for future research.

Potential and recent advances of microcarriers in repairing cartilage defects

Articular cartilage regeneration is one of the challenges faced by orthopedic surgeons. Microcarrier applications have made great advances in cartilage tissue engineering in recent years and enable cost-effective cell expansion, thus providing permissive microenvironments for cells. In addition, microcarriers can be loaded with proteins, factors, and drugs for cartilage regeneration. Some microcarriers also have the advantages of injectability and targeted delivery. The application of microcarriers with these characteristics can overcome the limitations of traditional methods and provide additional advantages. In terms of the transformation potential, microcarriers have not only many advantages, such as providing sufficient and beneficial cells, factors, drugs, and microenvironments for cartilage regeneration, but also many application characteristics; for example, they can be injected to reduce invasiveness, transplanted after microtissue formation to increase efficiency, or combined with other stents to improve mechanical properties. Therefore, this technology has enormous potential for clinical transformation. In this review, we focus on recent advances in microcarriers for cartilage regeneration. We compare the characteristics of microcarriers with other methods for repairing cartilage defects, provide an overview of the advantages of microcarriers, discuss the potential of microcarrier systems, and present an outlook for future development.

Translational potential of this article

We reviewed the advantages and recent advances of microcarriers for cartilage regeneration. This review could give many scholars a better understanding of microcarriers, which can provide doctors with potential methods for treating patients with cartilage injure.

A porcine acellular dermal matrix induces human fibroblasts to secrete hyaluronic acid by activating JAK2/STAT3 signalling

Human facial skin undergoes continuous ageing over a lifespan. At present, facial skin rejuvenation is mainly achieved by injecting filling materials. However, conventional materials lack long-term beneficial effects and can only rejuvenate the skin temporarily by physical filling. To overcome this shortcoming, this study developed a porcine acellular dermal matrix with a porous three-dimensional scaffold structure and containing natural growth factors (3D-GF-PADM). The average size of the 3D-GF-PADM particles was 33.415 μm, and the dynamic viscosity and elastic modulus were within ranges suitable for clinical applications. Our study revealed that the 3D-GF-PADM exhibited an extremely low α-gal epitope number (3.15 ± 0.84 × 10¹¹/mg) and DNA content, and no immunotoxicity, but contained abundant TGF-β1, VEGF and other growth factors. More importantly, this 3D-GF-PADM actively induced the synthesis of hyaluronic acid by fibroblasts of the host skin. Study at the molecular level further demonstrated that the 3D-GF-PADM activated the JAK2/STAT3 pathway, resulting in the upregulation of HAS2 expression, which led to an increase in hyaluronic acid synthesis. Our study developed a novel 3D-GF-PADM that can actively induce hyaluronic acid synthesis, which may be used clinically as a skin filling material to achieve long-term skin rejuvenation.

By activating the JAK2/STAT3 pathway, 3D-GF-PADM induces the production of hyaluronic acid in human fibroblasts.

Biological Considerations in Scaling Up Therapeutic Cell Manufacturing

Cell therapeutics - using cells as living drugs - have made advances in many areas of medicine. One of the most clinically studied cell-based therapy products is mesenchymal stromal cells (MSCs), which have shown promising results in promoting tissue regeneration and modulating inflammation. However, MSC therapy requires large numbers of cells, the generation of which is not feasible via conventional planar tissue culture methods. Scale-up manufacturing methods (e.g., propagation on microcarriers in stirred-tank bioreactors), however, are not specifically tailored for MSC expansion. These processes may, in principle, alter the cell secretome, a vital component underlying the immunosuppressive properties and clinical effectiveness of MSCs. This review outlines our current understanding of MSC properties and immunomodulatory function, expansion in commercial manufacturing systems, and gaps in our knowledge that need to be addressed for effective up-scaling commercialization of MSC therapy.

Successful Use of Human AB Serum to Support the Expansion of Adipose Tissue-Derived Mesenchymal Stem/Stromal Cell in a Microcarrier-Based Platform

Mesenchymal stem/stromal cells (MSC) are promising candidates for cell-based therapies and for the promotion of tissue repair, hence the increase of clinical trials in a worldwide scale. In particular, adipose tissue-derived stem/stromal cells (AT MSC) present easy accessibility and a rather straightforward process of isolation, providing a clear advantage over other sources. The high demand of cell doses (millions of cells/kg), needed for infusion in clinical settings, requires a scalable and efficient manufacturing of AT MSC under xenogeneic(xeno)-free culture conditions. Here we describe the successful use of human AB serum [10%(v/v)] as a culture supplement, as well as coating substrate for the expansion of these cells in microcarriers using (i) a spinner flask and (ii) a 500-mL mini-bioreactor (Applikon^TM Biotechnology). Cells were characterized by immunophenotype and multilineage differentiation potential. Upon an initial cell adhesion in the spinner flask of 35 ± 2.5%, culture reached a maximal cell density of 2.6 ± 0.1 × 10⁵ at day 7, obtaining a 15 ± 1-fold increase. The implementation of the culture in the 500-mL mini-bioreactor presented an initial cell adhesion of 22 ± 5%, but it reached maximal cell density of 2.7 ± 0.4 × 10⁵ at day 7, obtaining a 27 ± 8-fold increase. Importantly, in both stirred systems, cells retained their immunophenotype and multilineage differentiation potential (osteo-, chondro- and adipogenic lineages). Overall, the scalability of this microcarrier-based system presented herein is of major importance for the purpose of achieving clinically meaningful cell numbers.

Signaling Molecule-Immobilized Porous Particles with a Leaf-Stacked Structure as a Bioactive Filler System

The ultimate purpose of this study was to develop a bioactive filler system that would allow volume restoration (passive property) and continuous release of signaling molecules to recruit soft tissues (bioactive property) and thus effectively correct facial aging. To achieve this, we prepared porous particles with a leaf-stacked structure throughout the entire particle volume (LSS particles) using a simple heating-cooling technique. LSS particles were loaded with insulin-like growth factor-1 (IGF-1) and vascular endothelial growth factor (VEGF) separately, by immersing the particles in signaling molecule-containing solutions for target tissue recruitment (adipose by IGF-1 and blood vessels by VEGF). IGF-1 and VEGF were continuously released from LSS particles for 28 and 21 days in vitro, respectively, even without additional chemical/physical modifications, because of the unique morphology of the particles. Signaling molecules preserved their bioactivity in vitro (induction of adipogenic and angiogenic differentiation) and in vivo (recruitment of fat and blood vessels) for a sufficient period. Moreover, it was observed that the LSS particles themselves have stable volume retention characteristics in the body. Thus, we suggest that the signaling molecule-loaded LSS particles can function as a bioactive filler system for volume retention and target tissue regeneration.

Silk fibroin/gelatin microcarriers as scaffolds for bone tissue engineering

Microcarrier cell scaffolds have potential as injectable cell delivery vehicles or as building blocks for tissue engineering. The use of small cell carriers allows for a 'bottom up' approach to tissue assembly when moulding microparticles into larger structures, which can facilitate the introduction of hierarchy by layering different matrices and cell types, while evenly distributing cells through the structure. In this work, silk fibroin (SF), purified from Bombyx mori cocoons, was blended with gelatin (G) to produce materials composed of varying ratios of the two components (SF: G 25:75, 50:50, and 75:25). Cell compatibility to these materials was first confirmed in two-dimensional culture and found to be equivalent to standard tissue culture plastic, and better than SF or G alone. The mechanical properties of the blends were investigated and the blended materials were found to have increased Young's moduli over SF alone. Microcarriers of SF/G blends with defined diameters were generated in a reproducible manner through the use of an axisymmetric flow focussing device, constructed from off-the-shelf parts and fittings. These SF/G microcarriers supported adhesion of rat mesenchymal stem cells with high degrees of efficiency under dynamic culture conditions and, after culturing in osteogenic differentiation medium, cells were shown to have characteristics typical of osteoblasts. This work illustrates that microcarriers composed of SF/G blends are promising building blocks for osteogenic tissue engineering.

In vitro Engineering of a Skin Substitute Based on Adipose-Derived Stem Cells

In the field of wound healing, stem cell-based strategies are gaining importance for their regenerative potential. Adipose-derived stem cells (ADSCs) are a particular subset of mesenchymal stem cells present in the stromal-vascular fraction of the adipose tissue, today considered very attractive for their relative abundance and accessibility in the human body. However, ADSCs are still not routinely used in normal clinical practice. Several studies have also reported ADSC transplantation in association with biomaterials in an attempt to enhance the local retention and growth rate of the cells. The aim of our study was to evaluate the ability of ADSCs to build a dermal scaffold to be potentially used as a dermal substitute in the field of wound healing, with optimal biocompatibility and mechanical properties. ADSCs were defined as CD90-, CD73-, and CD105-positive cells. ADSCs turned out to be capable of secreting all the main components of the extracellular matrix (ECM) upon stimulation, thus efficiently producing a collagen and fibronectin-containing dermal matrix. We also checked whether the ADSC-produced dermal scaffold could be seeded with keratinocytes. The scaffolding material directly produced by ADSCs has several advantages when compared to the commercially available ones: it is easily obtained from the patients and it is 100% biocompatible and supports cell-ECM interaction. Moreover, it represents a possible powerful therapeutic tool for patients with chronic ulcers since it appears to be potentially grafted with keratinocytes layers, thus bypassing the classical two-step grafting procedure.

Epithelial defect repair in the auricle and auditory meatus by grafting with cultured adipose-derived mesenchymal stem cell aggregate-extracellular matrix

Background:

Several patients experience persistent otorrhea after a flawless surgical procedure because of insufficient epithelial healing. Several efforts, such as autologous tissue allograft and xenograft, have been made to halt otorrhea. However, a stable technology to induce temporal epithelial repair is yet to be established. Therefore, this study aims to investigate whether implantation of seeding adipose-derived mesenchymal stem cell (ADMSC) aggregates on extracellular matrix (ECM; herein, ADMSC aggregate-ECM) into damaged skin wound promotes skin regeneration.

Methods:

ADMSC aggregate-ECM was prepared using a previously described procedure that isolated ADMSCs from rabbits and applied to the auricle and auditory meatus wound beds of New Zealand white rabbits. Wound healing was assessed by general observation and hematoxylin and eosin (H&E) staining. Secretion of growth factor of the tissue was evaluated by western blotting. Two other groups, namely, ECM and control, were used. Comparisons of three groups were conducted by one-way analysis of variance analysis.

Results:

ADMSCs adhered tightly to the ECM and quickly formed cell sheets. At 2 weeks, general observation and H&E staining indicated that the wound healing rates in the ADMSC aggregate-ECM (69.02 ± 6.36%) and ECM (59.32 ± 4.10%) groups were higher than that in the control group (43.74 ± 12.15%; P = 0.005, P < 0.001, respectively) in ear auricle excisional wounds. At 7 weeks, The scar elevation index was evidently reduced in the ADMSC aggregate-ECM (2.08 ± 0.87) and ECM (2.31 ± 0.33) groups compared with the control group (4.06 ± 0.45; P < 0.001, P < 0.001, respectively). In addition, the scar elevation index of the ADMSC aggregate-ECM group reached the lowest rate 4 weeks in advance. In auditory meatus excisional wounds, the ADMSC aggregate-ECM group had the largest range of normal skin-like structure at 4 weeks. The ADMSC aggregate–ECM and ECM groups secreted increased amounts of growth factors that contributed to skin regeneration at weeks 1 and 2, respectively.

Conclusions:

ADMSC aggregate-ECM and ECM are effective repair materials for wound healing, especially ADMSC aggregate-ECM. This approach will provide a meaningful experimental basis for mastoid epithelium repair in subsequent clinical trials.

Biomaterials as cell carriers for augmentation of adipose tissue-derived stromal cell transplantation

Adipose tissue-derived stromal cells (ADSCs) contain lineage-committed progenitor cells that have the ability to differentiate into various cell types that may be useful for autologous cell transplantation to correct defects of skin, adipose, cartilage, bone, tendon, and blood vessels. The multipotent characteristics of ADSCs, as well as their abundance in the human body, make them an attractive potential resource for wound repair and applications to tissue engineering. ADSC transplantation has been used in combination with biomaterials, including cell sheets, hydrogel, and three-dimensional (3D) scaffolds based on chitosan, fibrin, atelocollagen, and decellularized porcine dermis, etc. Furthermore, low molecular weight heparin/protamine nanoparticles (LH/P NPs) have been used as an inducer of ADSC aggregation. The tissue engineering potential of these biomaterials as cell carriers is increased by the synergistic relationship between ADSCs and the biomaterials, resulting in the release of angiogenic cytokines and growth factors. In this review article, we describe the advantages of ADSC transplantation for tissue engineering, focusing on biomaterials as cell carriers which we have studied.

Fabrication of nanofibrous microcarriers mimicking extracellular matrix for functional microtissue formation and cartilage regeneration

Cartilage has rather limited capacities for self-repair and regeneration. To repair complexly shaped cartilage tissue defects, we propose the application of microtissues fabricated from bone marrow-derived mesenchymal stem cells (BMSCs) cultured in natural bionic nanofibrous microcarriers (NF-MCs). The NF-MCs were structurally and functionally designed to mimic natural extracellular matrix (ECM) by crosslinking dialdehyde bacterial cellulose (DBC) with DL-allo-hydroxylysine (DHYL) and complexing chitosan (CS) with DHYL through electrostatic interactions. The orthogonal design allows for fine tuning of fiber diameter, pore size, porosity, mechanical properties, and biodegradation rate of the NF-MC. BMSCs cultured in NF-MCs showed improved proliferation compared with those cultured in chitosan microcarriers (CS-MCs). After three-week culture under microgravity conditions, functional cartilage microtissues were generated. When implanted into a knee articular cartilage defect in mice, the microtissue showed superior in vivo cartilage repair as characterized by cell tracking, histology, micro CT image, and gait analysis. Versatile in natural biopolymer design and biomimetic in nanofibrous component embedded in macroporous microcarriers, these injectable NC-MCs demonstrate to be effective carriers for cell proliferation and differentiation. Furthermore, the functional microtissues also show their prospect in repair of cartilage tissue, and suggest their potential for other tissues in general.

Fabrication of Innovative Silk/Alginate Microcarriers for Mesenchymal Stem Cell Delivery and Tissue Regeneration

The aim of this study was to exploit silk fibroin’s properties to develop innovative composite microcarriers for mesenchymal stem cell (MSCs) adhesion and proliferation. Alginate microcarriers were prepared, added to silk fibroin solution, and then treated with ethanol to induce silk conformational transition. Microcarriers were characterized for size distribution, coating stability and homogeneity. Finally, in vitro cytocompatibility and suitability as delivery systems for MSCs were investigated. Results indicated that our manufacturing process is consistent and reproducible: silk/alginate microcarriers were stable, with spherical geometry, about 400 μm in average diameter, and fibroin homogeneously coated the surface. MSCs were able to adhere rapidly onto the microcarrier surface and to cover the surface of the microcarrier within three days of culture; moreover, on this innovative 3D culture system, stem cells preserved their metabolic activity and their multi-lineage differentiation potential. In conclusion, silk/alginate microcarriers represent a suitable support for MSCs culture and expansion. Since it is able to preserve MSCs multipotency, the developed 3D system can be intended for cell delivery, for advanced therapy and regenerative medicine applications.

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.

Breast Augmentation and Reconstruction from a Regenerative Medicine Point of View: State of the Art and Future Perspectives

Breast reconstruction and augmentation are very common procedures, yet the prevailing current methods utilize silicone implants that may have significant local complications requiring reoperation. Lipofillling is increasingly used to contour and is considered safe, however, its utility is limited by significant volume loss. A new approach could offer an alternative and increase the scope of patient choice. A small number of teams around the world are investigating a breast tissue engineering (TE) paradigm. Conventional breast TE concepts are based on seeding a scaffold with the patients' own stem cells. However, the clinical viability of many of these approaches is limited by their costs in relevant volumes. In this article the state of the art of tissue-engineered breast reconstruction is reviewed and future perspectives are presented and discussed.

Pharmacologically active microcarriers delivering BDNF within a hydrogel: Novel strategy for human bone marrow-derived stem cells neural/neuronal differentiation guidance and therapeutic secretome enhancement

Stem cells combined with biodegradable injectable scaffolds releasing growth factors hold great promises in regenerative medicine, particularly in the treatment of neurological disorders. We here integrated human marrow-isolated adult multilineage-inducible (MIAMI) stem cells and pharmacologically active microcarriers (PAMs) into an injectable non-toxic silanized-hydroxypropyl methylcellulose (Si-HPMC) hydrogel. The goal is to obtain an injectable non-toxic cell and growth factor delivery device. It should direct the survival and/or neuronal differentiation of the grafted cells, to safely transplant them in the central nervous system, and enhance their tissue repair properties. A model protein was used to optimize the nanoprecipitation conditions of the neuroprotective brain-derived neurotrophic factor (BDNF). BDNF nanoprecipitate was encapsulated in fibronectin-coated (FN) PAMs and the in vitro release profile evaluated. It showed a prolonged, bi-phasic, release of bioactive BDNF, without burst effect. We demonstrated that PAMs and the Si-HPMC hydrogel increased the expression of neural/neuronal differentiation markers of MIAMI cells after 1week. Moreover, the 3D environment (PAMs or hydrogel) increased MIAMI cells secretion of growth factors (b-NGF, SCF, HGF, LIF, PlGF-1, SDF-1α, VEGF-A & D) and chemokines (MIP-1α & β, RANTES, IL-8). These results show that PAMs delivering BDNF combined with Si-HPMC hydrogel represent a useful novel local delivery tool in the context of neurological disorders. It not only provides neuroprotective BDNF but also bone marrow-derived stem cells that benefit from that environment by displaying neural commitment and an improved neuroprotective/reparative secretome. It provides preliminary evidence of a promising pro-angiogenic, neuroprotective and axonal growth-promoting device for the nervous system.

STATEMENT OF SIGNIFICANCE

Combinatorial tissue engineering strategies for the central nervous system are scarce. We developed and characterized a novel injectable non-toxic stem cell and protein delivery system providing regenerative cues for central nervous system disorders. BDNF, a neurotrophic factor with a wide-range effect, was nanoprecipitated to maintain its structure and released in a sustained manner from novel polymeric microcarriers. The combinatorial 3D support, provided by fibronectin-microcarriers and the hydrogel, to the mesenchymal stem cells guided the cells towards a neuronal differentiation and enhanced their tissue repair properties by promoting growth factors and cytokine secretion. The long-term release of physiological doses of bioactive BDNF, combined to the enhanced secretion of tissue repair factors from the stem cells, constitute a promising therapeutic approach.

Decellularized adipose tissue microcarriers as a dynamic culture platform for human adipose-derived stem/stromal cell expansion

With the goal of designing a clinically-relevant expansion strategy for human adipose-derived stem/stromal cells (ASCs), methods were developed to synthesize porous microcarriers derived purely from human decellularized adipose tissue (DAT). An electrospraying approach was applied to generate spherical DAT microcarriers with an average diameter of 428 ± 41 μm, which were soft, compliant, and stable in long-term culture without chemical crosslinking. Human ASCs demonstrated enhanced proliferation on the DAT microcarriers relative to commercially-sourced Cultispher-S microcarriers within a spinner culture system over 1 month. ASC immunophenotype was maintained post expansion, with a trend for reduced expression of the cell adhesion receptors CD73, CD105, and CD29 under dynamic conditions. Upregulation of the early lineage-specific genes PPARγ, LPL, and COMP was observed in the ASCs expanded on the DAT microcarriers, but the cells retained their multilineage differentiation capacity. Comparison of adipogenic and osteogenic differentiation in 2-D cultures prepared with ASCs pre-expanded on the DAT microcarriers or Cultispher-S microcarriers revealed similar adipogenic and enhanced osteogenic marker expression in the DAT microcarrier group, which had undergone a higher population fold change. Further, histological staining results suggested a more homogeneous differentiation response in the ASCs expanded on the DAT microcarriers as compared to either Cultispher-S microcarriers or tissue culture polystyrene. A pilot chondrogenesis study revealed higher levels of chondrogenic gene and protein expression in the ASCs expanded on the DAT microcarriers relative to all other groups, including the baseline controls. Overall, this study demonstrates the promise of applying dynamic culture with tissue-specific DAT microcarriers as a means of deriving regenerative cell populations.

Future Prospects for Scaffolding Methods and Biomaterials in Skin Tissue Engineering: A Review

Over centuries, the field of regenerative skin tissue engineering has had several advancements to facilitate faster wound healing and thereby restoration of skin. Skin tissue regeneration is mainly based on the use of suitable scaffold matrices. There are several scaffold types, such as porous, fibrous, microsphere, hydrogel, composite and acellular, etc., with discrete advantages and disadvantages. These scaffolds are either made up of highly biocompatible natural biomaterials, such as collagen, chitosan, etc., or synthetic materials, such as polycaprolactone (PCL), and poly-ethylene-glycol (PEG), etc. Composite scaffolds, which are a combination of natural or synthetic biomaterials, are highly biocompatible with improved tensile strength for effective skin tissue regeneration. Appropriate knowledge of the properties, advantages and disadvantages of various biomaterials and scaffolds will accelerate the production of suitable scaffolds for skin tissue regeneration applications. At the same time, emphasis on some of the leading challenges in the field of skin tissue engineering, such as cell interaction with scaffolds, faster cellular proliferation/differentiation, and vascularization of engineered tissues, is inevitable. In this review, we discuss various types of scaffolding approaches and biomaterials used in the field of skin tissue engineering and more importantly their future prospects in skin tissue regeneration efforts.

Isolation and culture of primary rat adipose derived stem cells using porous biopolymer microcarriers

Adipose-derived stem cells (ADSCs) are an attractive source of material for mesenchymal stem cell research due to the abundance of adipose and relative ease of access compared with bone marrow. A key consideration for research is whether cell isolation methods can be improved, to reduce the process steps needed to isolate and expand cell material. In the current study, we used macroporous biopolymer microcarriers to isolate primary ADSCs. We found that the method was capable of isolating ADSCs that were subsequently capable of being transferred to culture dishes and expanded in vitro. Moreover, flow cytometry revealed that they expressed typical stem cell markers and were capable of undergoing tri-lineage differentiation. In summary, it is feasible to use biopolymer microcarriers for retrieval of viable ADSCs that retain identity markers of stem cell function.

Adipose regeneration and implications for breast reconstruction: update and the future

The evolution of breast reconstruction and management of breast cancer has evolved significantly since the earliest descriptions in the Edwin Smith Papyrus (3,000 BC). The development of surgical and scientific expertise has changed the way that women are managed, and plastic surgeons are now able to offer a wide range of reconstructive options to suit individual needs. Beyond the gold standard autologous flap based reconstructions, regenerative therapies promise the elimination of donor site morbidity whilst providing equivalent aesthetic and functional outcomes. Future research aims to address questions regarding ideal cell source, optimisation of scaffold composition and interaction of de novo adipose tissue in the microenvironment of breast cancer.

Serum-free media formulations are cell line-specific and require optimization for microcarrier culture

BACKGROUND AIMS

Mesenchymal stromal cells (MSCs) are being investigated as potential cell therapies for many different indications. Current methods of production rely on traditional monolayer culture on tissue-culture plastic, usually with the use of serum-supplemented growth media. However, the monolayer culturing system has scale-up limitations and may not meet the projected hundreds of billions to trillions batches of cells needed for therapy. Furthermore, serum-free medium offers several advantages over serum-supplemented medium, which may have supply and contaminant issues, leading to many serum-free medium formulations being developed.

METHODS

We cultured seven MSC lines in six different serum-free media and compared their growth between monolayer and microcarrier culture.

RESULTS

We show that (i) expansion levels of MSCs in serum-free monolayer cultures may not correlate with expansion in serum-containing media; (ii) optimal culture conditions (serum-free media for monolayer or microcarrier culture) differ for each cell line; (iii) growth in static microcarrier culture does not correlate with growth in stirred spinner culture; (iv) and that early cell attachment and spreading onto microcarriers does not necessarily predict efficiency of cell expansion in agitated microcarrier culture.

CONCLUSIONS

Current serum-free media developed for monolayer cultures of MSCs may not support MSC proliferation in microcarrier cultures. Further optimization in medium composition will be required for microcarrier suspension culture for each cell line.

Curbing Inflammation in Skin Wound Healing: A Review

Wound healing is a complex regulated process that results in skin scar formation in postnatal mammals. Chronic wounds are major medical problems that can confer devastating consequences. Currently, there are no treatments to prevent scarring. In the early fetus wounds heal without scarring and the healing process is characterized by relatively less inflammation compared to adults; therefore, research aimed at reducing the inflammatory process related to wound healing might speed healing and improve the final scar appearance.

Feasibility of human hair follicle-derived mesenchymal stem cells/CultiSpher(®)-G constructs in regenerative medicine

The use of human mesenchymal stem cells (hMSCs) in cell therapies has increased the demand for strategies that allow efficient cell scale-up. Preliminary data on the three-dimensional (3D) spinner culture describing the potential use of microcarriers for hMSCs culture scale-up have been reported. We exploited a rich source of autologous stem cells (human hair follicle) and demonstrated the robust in vitro long-term expansion of human hair follicle-derived mesenchymal stem cells (hHF-MSCs) by using CultiSpher(®)-G microcarriers. We analyzed the feasibility of 3D culture by using hHF-MSCs/CultiSpher(®)-G microcarrier constructs for its potential applicability in regenerative medicine by comparatively analyzing the performance of hHF-MSCs adhered to the CultiSpher(®)-G microspheres in 3D spinner culture and those grown on the gelatin-coated plastic dishes (2D culture), using various assays. We showed that the hHF-MSCs seeded at various densities quickly adhered to and proliferated well on the microspheres, thus generating at least hundreds of millions of hHF-MSCs on 1 g of CultiSpher(®)-G within 12 days. This resulted in a cumulative cell expansion of greater than 26-fold. Notably, the maximum and average proliferation rates in 3D culture were significantly greater than that of the 2D culture. However, the hHF-MSCs from both the cultures retained surface marker and nestin expression, proliferation capacity and differentiation potentials toward adipocytes, osteoblasts and smooth muscle cells and showed no significant differences as evidenced by Edu incorporation, cell cycle, colony formation, apoptosis, biochemical quantification and qPCR assays.

Past, present, and future of microcarrier-based tissue engineering

The top issue in tissue engineering is how to obtain more seed cells quickly and to preserve their characteristic morphology during in vitro expansion culture of cells. Microcarriers can help to amplify cell numbers and maintain the appropriate phenotype for tissue repair and restoration of function. In addition, microtissue with cell microcarriers can be used to repair diseased tissues or organs. This review introduces the materials used for, and classification of, microcarriers and the improvements in, and potential applications of, microtissues with cell microcarriers in tissue engineering.

The effect of medium selection on adipose-derived stem cell expansion and differentiation: implications for application in regenerative medicine

The use of adipose-derived stem cells is wide-spread in both basic biology and regenerative medicine, due to the abundance of adipose tissue and the multipotent differentiation potential of the cells. However, the methods used to isolate and culture cells vary greatly between different research groups. Identification of medium formulations which provide rapid cell expansion while maintaining cell phenotype would have clear advantages. We compared growth and differentiation potential along the adipogenic lineage in human ADSCs in nine different media. We further assessed induced and spontaneous differentiation along the adipogenic, chondrogenic and osteogenic lineage in three different media. There was significant variation in the rate of growth between different media. All media supported ADSC phenotype and adipogenic differentiation, although there was variation between the different media. Differentiation along the adipogenic, chondrogenic and osteogenic lineages in the three media was confirmed, with some upregulation of specific genes observed when cells were left to spontaneously differentiate. Our study shows a direct comparison of human ADSCs grown in different media, both reported in the literature and commercially available. It indicates that rapid proliferation occurs most often in media which contain 10 % foetal bovine serum and that differentiation along different lineages can be induced but also occurs spontaneously once cells become confluent. These data provide a tool for other researchers to facilitate the choice of medium formulation most appropriate for different applications.

Autologous platelet-rich plasma: a biological supplement to enhance adipose-derived mesenchymal stem cell expansion

Currently the use of non-autologous cell culture media (e.g., animal-derived or allogeneic serum) for clinical applications of mesenchymal stem cells (MSCs) is criticized by regulatory agencies. Autologous platelet-rich plasma (PRP) is proposed as a safer alternative medium supplement for adipose-derived mesenchymal stem cells (AT-MSC) culture. To study its efficiency on cell proliferation, AT-MSCs were cultured for 10 days in media supplemented with different concentrations of autologous non-activated PRP (nPRP) or thrombin-activated PRP (tPRP) (1-60%). AT-MSC proliferation, cell phenotype, multipotency capacity, and chromosome stability were assessed and compared to AT-MSCs expanded in a classical medium supplemented with 10% of fetal bovine serum (FBS). Culture media supplemented with nPRP showed dose-dependent higher AT-MSC proliferation than did FBS or tPRP. Twenty percent nPRP was the most effective concentration to promote cell proliferation. This condition increased 13.9 times greater AT-MSC number in comparison to culture with FBS, without changing the AT-MSC phenotype, differentiation capacity, and chromosome status. We concluded that 20% autologous nPRP is a safe, efficient, and cost-effective supplement for AT-MSC expansion. It should be considered as an alternative to FBS or other nonautologous blood derivatives. It could serve as a potent substitute for the validation of future clinical protocols as it respects good manufacturing practices and regulatory agencies' standards.

Engineering stem cell fate with biochemical and biomechanical properties of microcarriers

Microcarriers have been widely used for various biotechnology applications because of their high scale-up potential, high reproducibility in regulating cellular behavior, and well-documented compliance with current Good Manufacturing Practices (cGMP). Recently, microcarriers have been emerging as a novel approach for stem cell expansion and differentiation, enabling potential scale-up of stem cell-derived products in large bioreactors. This review summarizes recent advances of using microcarriers in mesenchymal stem cell (MSC) and pluripotent stem cell (PSC) cultures. From the reported data, efficient expansion and differentiation of stem cells on microcarriers rely on their ability to modulate cell shape (i.e. round or spreading) and cell organization (i.e. aggregate size). Nonetheless, current screening of microcarriers remains empirical, and accurate understanding of how stem cells interact with microcarriers still remains unknown. This review suggests that accurate characterization of biochemical and biomechanical properties of microcarriers is required to fully exploit their potential in regulating stem cell fate decision. Due to the variety of microcarriers, such detailed analyses should lead to the rational design of application-specific microcarriers, enabling the exploitation of reproducible effects for large scale biomedical applications.

Interactions of the Extracellular Matrix and Progenitor Cells in Cutaneous Wound Healing

SIGNIFICANCE

Both chronic wounds and excessive scar formation after cutaneous injury create a formidable clinical problem resulting in considerable morbidity and healthcare expenditure. The deposition and remodeling of extracellular matrix (ECM) components are critical processes in cutaneous healing. Understanding the role of the ECM in directing progenitor and reparative cell fate and activities during wound repair is required to improve wound-care strategies.

RECENT ADVANCES

In addition to providing structural integrity, the ECM is recognized to play critical roles in regulating progenitor and reparative cell behaviors such as migration, differentiation, proliferation, and survival. The ECM dictates these activities through its binding of adhesion receptors as well as its ability to regulate growth factor bioavailability and signaling. More recently, a key role for mechanical control of cell fate through interaction with the ECM has emerged.

CRITICAL ISSUES

Despite significant advances in understanding the pathophysiology of cutaneous wound repair, problematic wounds remain a significant healthcare challenge. Regenerative medical strategies that either target endogenous stem cells or utilize applications of exogenous stem cell populations have emerged as promising approaches to pathologic wounds. However, the identification of smart biomaterials and matrices may allow for further optimization of such therapies.

FUTURE DIRECTIONS

An efficient and appropriate healing response in the skin postinjury is regulated by a fine balance of the quantity and quality of ECM proteins. A more complete understanding of ECM regulation of the cell fate and activities during cutaneous wound repair is vital for the development of novel treatment strategies for improvement of cutaneous healing.

A temperature-cured dissolvable gelatin microsphere-based cell carrier for chondrocyte delivery in a hydrogel scaffolding system

In this study, a novel therapeutic cell delivery methodology in the form of hydrogel encapsulating cell-laden microspheres was developed and investigated. As a model cell for cartilage tissue engineering, chondrocytes were successfully encapsulated in gelatin-based microspheres (mostly of diameter 50-100 μm, centred at 75-100 μm) with high cell viability during the formation of microspheres via a water-in-oil single emulsion process under a low temperature without any chemical treatment. These cell-laden microspheres were then encapsulated in alginate-based hydrogel constructs. By elevating the temperature to 37°C, the cell-laden microspheres were completely dissolved within 2 days, resulting in the same number of same-sized spherical cavities in hydrogel bulk, along with which the encapsulated cells were released from the microspheres and suspended inside the cavities to be cultivated for further development. In this cell delivery system, the microspheres played a dual role as both removable cell vehicles and porogens for creation of the intra-hydrogel cavities, in which the delivered cells were provided with both free living spaces and a better permeable environment. This temperature-cured dissolvable gelatin microsphere-based cell carrier (tDGMC) associating with cell-laden hydrogel scaffold was attempted and evaluated through WST-1, quantitative polymerase chain reaction, biochemical assays and various immunohistochemistry and histology stains. The results indicate that tDGMC technology can facilitate the delivery of chondrocytes, as a non-anchorage-dependent therapeutic cell, with significantly greater efficiency.

Microcarrier culture for efficient expansion and osteogenic differentiation of human fetal mesenchymal stem cells

Stirred microcarrier (MC) culture has been suggested as the method of choice for supplying large volumes of mesenchymal stem cells (MSCs) for bone tissue engineering. In this study, we show that in addition to the improvement in cell expansion capacity, MSCs propagated and harvested from MC culture also demonstrate higher osteogenic potency when differentiated in vivo or in vitro in three-dimensional (3D) scaffold cultures as compared with traditional monolayer (MNL) cultures. Cytodex 3 microcarrier-expanded human fetal MSC (hfMSC) cultures (MC-hfMSCs) achieved 12- to 16-fold expansion efficiency (6×10⁵–8×10⁵ cells/mL) compared to 4- to 6-fold (1.2×10⁵–1.8×10⁵ cells/mL) achieved by traditional MNL-expanded hfMSC culture (MNL-hfMSCs; p<0.05). Both MC-hfMSCs and MNL-hfMSCs maintained similar colony-forming capacity, doubling times, and immunophenotype postexpansion. However, when differentiated under in vitro two-dimensional (2D) osteogenic conditions, MC-hfMSCs exhibited a 45-fold reduction in alkaline phosphatase level and a 37.5% decrease in calcium deposition compared with MNL-hfMSCs (p<0.05). Surprisingly, when MC-hfMSCs and MNL-hfMSCs were seeded on 3D macroporous scaffold culture or subcutaneously implanted into nonobese diabetic/severe combined immunodeficient mice, MC-hfMSCs deposited 63.5% (p<0.05) more calcium and formed 47.2% (p<0.05) more bone volume, respectively. These results suggest that the mode of hfMSC growth in the expansion phase affects the osteogenic potential of hfMSCs differently in various differentiation platforms. In conclusion, MC cultures are advantageous over MNL cultures in bone tissue engineering because MC-hfMSCs have improved cell expansion capacity and exhibit higher osteogenic potential than MNL-hfMSCs when seeded in vitro into 3D scaffolds or implanted in vivo.

Flow cytometric cell sorting and in vitro pre-osteoinduction are not requirements for in vivo bone formation by human adipose-derived stromal cells

Human adipose-derived stromal cells (hASCs) are a promising cell source for bone tissue engineering. However, before the clinical application of hASCs for the treatment of bone defects, key questions require answers, including whether pre-osteoinduction (OI) and flow cytometric cell purification are indispensible steps for in vivo bone formation by hASCs. In this study, hASCs were purified by flow cytometric cell sorting (FCCS). The osteogenic capabilities of hASCs and purified hASCs with or without pre-osteoinduction were examined through in vitro and in vivo experiments. We found that pre-OI enhanced the in vitro osteogenic capacity of hASCs. However, 8 weeks after in vivo implantation, there were no significant differences between hASCs and hASCs that had undergone OI (hASCs+OI) or between purified hASCs and purified hASCs+OI (P>0.05). Interestingly, we also found that purified hASCs had an osteogenic potential similar to that of unpurified hASCs in vitro and in vivo. These results suggest that FCCS and in vitro pre-OI are not requirements for in vivo bone formation by hASCs.

Novel macro-microporous gelatin scaffold fabricated by particulate leaching for soft tissue reconstruction with adipose-derived stem cells

The restoration of body contours as shaped by adipose tissue remains a clinical challenge specifically in patients who have experienced loss of contour due to trauma, surgical removal of tumours or congenital abnormalities. We have developed a novel macro-microporous biomaterial for use in soft tissue re-bulking and augmentation. Alginate beads provided the pore template for the construct. Incorporation, and subsequent dissolution, of the beads within a 7 % (w/v) gelatin matrix, produced a highly porous scaffold with an average pore size of 2.01 ± 0.08 mm. The ability of this scaffold to support the in vitro growth and differentiation of human adipose-derived stem cells (ADSCs) was then investigated. Histological analysis confirmed that the scaffold itself provided a suitable environment to support the growth of ADSCs on the scaffold walls. When delivered into the macropores in a fibrin hydrogel, ADSCs proliferated and filled the pores. In addition, ADSCs could readily be differentiated along the adipogenic lineage. These results therefore describe a novel scaffold that can support the proliferation and delivery of ADSCs. The scaffold is the first stage in developing a clinical alternative to current treatment methods for soft tissue reconstruction.

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.