Cartilage tissue engineering with novel nonwoven structured biomaterial based on hyaluronic acid benzyl ester

Anatomy, molecular structures, and hyaluronic acid - Gelatin injectable hydrogels as a therapeutic alternative for hyaline cartilage recovery: A review

Cartilage damage caused by trauma or osteoarthritis is a common joint disease that can increase the social and economic burden in society. Due to its avascular characteristics, the poor migration ability of chondrocytes, and a low number of progenitor cells, the self-healing ability of cartilage defects has been significantly limited. Hydrogels have been developed into one of the most suitable biomaterials for the regeneration of cartilage because of its characteristics such as high-water absorption, biodegradation, porosity, and biocompatibility similar to natural extracellular matrix. Therefore, the present review article presents a conceptual framework that summarizes the anatomical, molecular structure and biochemical properties of hyaline cartilage located in long bones: articular cartilage and growth plate. Moreover, the importance of preparation and application of hyaluronic acid - gelatin hydrogels for cartilage tissue engineering are included. Hydrogels possess benefits of stimulating the production of Agc1, Col2α1-IIa, and SOX9, molecules important for the synthesis and composition of the extracellular matrix of cartilage. Accordingly, they are believed to be promising biomaterials of therapeutic alternatives to treat cartilage damage.

Water-insoluble fibres, threads, and fabrics from lauroyl derivatives of hyaluronan

Hyaluronan (HA) is a naturally occurring polysaccharide widely used in medicine and cosmetics. To further broaden its potential, various HA derivatives have been developed with the aim of reducing solubility, slowing degradation, or providing other beneficial properties. However, for most medical applications, these derivatives must be processed into suitable forms. Here we present water-insoluble fibres prepared from lauroyl-modified HA using a wet spinning process. Important properties of the fibres, such as swelling or the degradation rate, can be fine-tuned by adjusting the degree of HA modification. Due to their mechanical properties, the lauroyl HA fibres can be easily processed into threads and subsequently into fabrics of various sizes, shapes, and degrees of porosity. In addition, in vitro cytotoxicity testing of the fibres showed that they were non-cytotoxic. Overall, our results suggest that lauroyl HA fibres are a promising material that could be used to develop a variety of medical devices.

Cell therapies for chondral defects of the talus: a systematic review

Background

This systematic review investigated the efficacy and safety of surgical procedures augmented with cell therapies for chondral defects of the talus.

Methods

The present systematic review was conducted according to the 2020 PRISMA guidelines. PubMed, Google scholar, Embase, and Scopus databases were accessed in March 2022. All the clinical trials investigating surgical procedures for talar chondral defects augmented with cell therapies were accessed. The outcomes of interest were to investigate whether surgical procedures augmented with cell therapies promoted improvement in patients reported outcomes measures (PROMs) with a tolerable rate of complications.

Results

Data from 477 procedures were retrieved. At a mean follow-up of 34.8 ± 9.7 months, the Visual Analogic Scale (VAS) improved of 4.4/10 (P = 0.002) and the American Orthopaedic Foot and Ankle Score (AOFAS) of 31.1/100 (P = 0.0001) points. No improvement was found in Tegner score (P = 0.4). Few articles reported data on complications. At last follow-up, the rate of reoperation and failure were 0.06% and 0.03%, respectively. No graft delamination or hypertrophy was observed.

Conclusion

The current evidence suggests that cell therapies may be effective and safe to enhance surgical procedures for chondral defects of the talus. These results should be considered within the limitations of the present study. The current literature should be enriched with randomized controlled clinical trials with larger population size and longer follow-up.

Efficient sterilization system combining flavonoids and hyaluronic acid with metal organic frameworks as carrier

Bacterial infections can cause many human diseases, which are closely related to people's health. Nowadays, antibiotics are mainly used to treat bacterial infections, but the widespread use of antibiotics can also lead to bacterial resistance. Therefore, effective treatment of bacterial infections is an urgent problem to be solved. In this article, a multifunctional therapeutic material with antibacterial properties was designed and synthesized. First, the porous media material ZIF-8 was synthesized, and applied to load hesperidin. When the load is completed, a layer of hyaluronic acid (HA) is uniformly wrapped on surface of the material. Such materials have high stability and high drug-carrying capacity, and can be slowly released in vivo. The HA coated on surface can also promote penetration of active ingredients into cells and give full play to antibacterial ability. Results of in vitro and in vivo antibacterial tests show that synergy between the materials enhances antibacterial activity which is related to dose. The material achieves high-efficiency antibacterial effects by increasing the permeability of cell membranes and destroying the integrity of bacteria. At same time, the material does not show obvious side effects. Therefore, the material seems to be a promising antibacterial agent with good biocompatibility and strong antibacterial activity.

The Influence of Hyaluronic Acid Biofunctionalization of a Bovine Bone Substitute on Osteoblast Activity In Vitro

Bovine bone substitute materials (BSMs) are used for oral bone regeneration. The objective was to analyze the influence of BSM biofunctionalization via hyaluronic acid (HA) on human osteoblasts (HOBs). BSMs with ± HA were incubated with HOBs including HOBs alone as a negative control. On days 3, 7 and 10, cell viability, migration and proliferation were analyzed by fluorescence staining, scratch wound assay and MTT assay. On days 3, 7 and 10, an increased cell viability was demonstrated for BSM+ compared with BSM- and the control (each p ≤ 0.05). The cell migration was enhanced for BSM+ compared with BSM- and the control after day 3 and day 7 (each p ≤ 0.05). At day 10, an accelerated wound closure was found for the control compared with BSM+/- (each p < 0.05). The highest proliferation rate was observed for BSM+ on day 3 (p ≤ 0.05) followed by BSM- and the control (each p ≤ 0.05). At day 7, a non-significantly increased proliferation was shown for BSM+ while the control was higher than BSM- (each p < 0.05). The least proliferation activity was observed for BSM- (p < 0.05) at day 10. HA biofunctionalization of the BSMs caused an increased HOB activity and might represent a promising alternative to BSM- in oral bone regeneration.

Isolation of Chondrocytes from Human Cartilage and Cultures in Monolayer and 3D

Chondrocytes are the only cell type in cartilage. The dense cartilage extracellular matrix surrounding the chondrocytes makes isolating these cells a complex and lengthy task that subjects the cells to harsh conditions. Protocols to isolate expand and maintain these cells have been improved over the years, providing ways to obtain viable cells for tissue engineering and clinical applications. Here we describe a method to obtain populations of chondrocytes that are able to expand and maintain a native-like phenotype.

Comparison of Chitosan-Based Liquid Scaffold and Hyaluronic Acid-Based Soft Scaffold for Treatment of Talus Osteochondral Lesions

BACKGROUND

The aim of this study was to evaluate the clinical and radiologic results of 2 different scaffolds with hyaluronan or chitosan-based structure used in the treatment of talus osteochondral lesions.

METHODS

Eighty-one patients who underwent chondral lesion repair with hyaluronan (n = 42) or chitosan-based (n = 39) scaffold were included. American Orthopaedic Foot & Ankle Society (AOFAS) and visual analog scale (VAS) scores were evaluated within and between groups preoperatively and at the 3rd, 12th, and 24th month postoperatively. In all patients, magnetic resonance imaging was performed between the 12 and 18th month postoperatively and compared with magnetic resonance observation of cartilage repair tissue (MOCART) scoring.

RESULTS

Within-group evaluations revealed significant improvements in AOFAS and VAS scores at postoperative 3 and 12 months. The postoperative 24th-month results of AOFAS scores in any group did not differ significantly from the 12th-month results. There was no significant difference between the groups in comparison of AOFAS, VAS, and MOCART scores at any time period.

CONCLUSION

Both scaffolds were found to be effective in cartilage healing but had no clinical or radiologic superiority to each other. This is the first study to compare the use of different cell-free scaffold types in osteochondral defects of the talus.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Matrix-Augmented Bone Marrow Stimulation With a Polyglycolic Acid Membrane With Hyaluronan vs Microfracture in Local Cartilage Defects of the Femoral Condyles: A Multicenter Randomized Controlled Trial

Background

Microfracture (MF) is an established operative treatment for small, localized chondral defects of the knee joint. There is evidence from animal studies that matrix augmentation of bone marrow stimulation (m-BMS) can improve the quality of the repair tissue formation.

Purpose

To evaluate the therapeutic outcome of a matrix made of polyglycolic acid and hyaluronan as compared with a conventional MF technique.

Study Design

Randomized controlled trial; Level of evidence, 1.

Methods

Patients between the ages of 18 and 68 years who had an articular femoral cartilage defect of 0.5 to 3 cm² in the weightbearing area of the femoral condyles with indication for MF were included in this study. Patients were randomized and treated with either MF or m-BMS with Chondrotissue. Defect filling, as assessed on magnetic resonance imaging (MRI), at postoperative 12 weeks was defined as the primary outcome measure, with follow-up MRI at weeks 54 and 108. Follow-up data were also collected at 12, 54, and 108 weeks after surgery and included patient-reported clinical scores: visual analog scale for pain, Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee score, and 36-Item Short Form Health Survey.

Results

MRI scans confirmed cartilage repair tissue formation in both groups 12 weeks after treatment. There was no significant difference between the m-BMS and MF groups in the percentage of defect filling at 12, 54, and 108 weeks postoperatively. No significant difference was found in terms of patient-reported clinical scores. Both groups showed significant improvement in 4 KOOS subscales-Pain, Activities of Daily Living, Sport and Recreation, and Quality of Life-at 54 and 108 weeks after treatment.

Conclusion

This is the first randomized controlled trial comparing m-BMS with a polyglycolic acid matrix with hyaluronan with MF. The use of the Chondrotissue implant in m-BMS has been proven to be a safe procedure. No difference was found between m-BMS and MF in terms of patient-reported outcome scores and MRI assessment until postoperative 2 years. Long-term follow-up studies including histological assessment are desirable for further investigation.

Registration

EUCTR2011-003594-28-DE (EU Clinical Trials Register).

Evaluation of scaffold microstructure and comparison of cell seeding methods using micro-computed tomography-based tools

Micro-computed tomography (micro-CT) provides a means to analyse and model three-dimensional (3D) tissue engineering scaffolds. This study proposes a set of micro-CT-based tools firstly for evaluating the microstructure of scaffolds and secondly for comparing different cell seeding methods. The pore size, porosity and pore interconnectivity of supercritical CO2 processed poly(l-lactide-co-ɛ-caprolactone) (PLCL) and PLCL/β-tricalcium phosphate scaffolds were analysed using computational micro-CT models. The models were supplemented with an experimental method, where iron-labelled microspheres were seeded into the scaffolds and micro-CT imaged to assess their infiltration into the scaffolds. After examining the scaffold architecture, human adipose-derived stem cells (hASCs) were seeded into the scaffolds using five different cell seeding methods. Cell viability, number and 3D distribution were evaluated. The distribution of the cells was analysed using micro-CT by labelling the hASCs with ultrasmall paramagnetic iron oxide nanoparticles. Among the tested seeding methods, a forced fluid flow-based technique resulted in an enhanced cell infiltration throughout the scaffolds compared with static seeding. The current study provides an excellent set of tools for the development of scaffolds and for the design of 3D cell culture experiments.

Synthesis and Characterization of Covalently Crosslinked pH-Responsive Hyaluronic Acid Nanogels: Effect of Synthesis Parameters

Stable hyaluronic acid nanogels were obtained following the water-in-oil microemulsion method by covalent crosslinking with three biocompatible crosslinking agents: Divinyl sulfone, 1,4-butanediol diglycidyl ether (BDDE), and poly(ethylene glycol) bis(amine). All nanoparticles showed a pH-sensitive swelling behavior, according to the pKa value of hyaluronic acid, as a consequence of the ionization of the carboxylic moieties, as it was corroborated by zeta potential measurements. QELS studies were carried out to study the influence of the chemical structure of the crosslinking agents on the particle size of the obtained nanogels. In addition, the effect of the molecular weight of the biopolymer and the degree of crosslinking on the nanogels dimensions was also evaluated for BDDE crosslinked nanoparticles, which showed the highest pH-responsive response.

Neodermis Formation in Full Thickness Wounds Using an Esterified Hyaluronic Acid Matrix

The role of the dermis is essential for the proper orchestration of all phases of the normal wound healing process. Wounds with seriously damaged or even absent dermis consistently show seriously impaired wound healing and/or long-term complications such as hypertrophic scarring. Replacing a damaged dermis requires a dermal matrix that is compatible with, or even stimulates, the process of wound healing. Hyaluronic acid (HA), in an esterified form, is among the many matrices that are available. HA has been used in a number of indications, such as ulcers (ie, diabetic foot ulcers and venous leg ulcers), trauma, including burns, and for the repair of contractures and hypertrophic scars. The shorter healing time and the decrease of recurring hypertrophy demonstrate the efficiency of HA-derived matrices. Biopsies, taken up to 12 months post-reconstruction show a neodermis that histologically is largely comparable to normal skin, which probably is a function of HA playing such a pivotal role in normal, unwounded skin, as well as in the process of healing.

Regenerative Medicine: A Review of the Evolution of Autologous Chondrocyte Implantation (ACI) Therapy

Articular cartilage is composed of chondrons within a territorial matrix surrounded by a highly organized extracellular matrix comprising collagen II fibrils, proteoglycans, glycosaminoglycans, and non-collagenous proteins. Damaged articular cartilage has a limited potential for healing and untreated defects often progress to osteoarthritis. High hopes have been pinned on regenerative medicine strategies to meet the challenge of preventing progress to late osteoarthritis. One such strategy, autologous chondrocyte implantation (ACI), was first reported in 1994 as a treatment for deep focal articular cartilage defects. ACI has since evolved to become a worldwide well-established surgical technique. For ACI, chondrocytes are harvested from the lesser weight bearing edge of the joint by arthroscopy, their numbers expanded in monolayer culture for at least four weeks, and then re-implanted in the damaged region under a natural or synthetic membrane via an open joint procedure. We consider the evolution of ACI to become an established cell therapy, its current limitations, and on-going strategies to improve its efficacy. The most promising developments involving cells and natural or synthetic biomaterials will be highlighted.

Managing Wounds with Exposed Bone and Tendon with an Esterified Hyaluronic Acid Matrix (eHAM): A Literature Review and Personal Experience

The loss of extracellular matrix in combination with the exposure of structures such as bone and tendon pose a major challenge; the development of granulation tissue and subsequent reepithelialization over these structures is extremely slow and often may not happen at all. Replacement of the matrix has been shown to significantly increase the chances of healing since, with revascularization of the matrix, a wound bed is created that may either heal by secondary intention or via the application of a skin graft. A literature search on an esterified hyaluronic acid-based matrix (eHAM) returned five articles on the treatment of wounds with tendon and bone loss in which the eHAM was used. The etiologies of the wounds described varied among the articles, as did treatment modalities. However, all of them received proper debridement of necrosis with subsequent (although not always immediately) application of the eHAM. A very high percentage of all wounds reached the different primary endpoints in the studies, which were complete reepithelialization, complete coverage with granulation tissue and/or 10% coverage of the original wound size with epithelium, the latter being a strong indicator of the wound continuing to heal. The individual authors concluded that the esterified hyaluronic acid matrix (eHAM) is a valuable tool to assist in the complete healing of difficult to heal wounds.

[Current overview of cartilage regeneration procedures]

BACKGROUND

Cartilage is an avascular, alymphatic and non-innervated tissue with limited intrinsic repair potential. The high prevalence of cartilage defects and their tremendous clinical importance are a challenge for all treating physicians.

AIM

This article provides the reader with an overview about current cartilage treatment options and their clinical outcome.

METHODS

Microfracture is still considered the gold standard in the treatment of small cartilage lesions. Small osteochondral defects can be effectively treated with the autologous osteochondral transplantation system. Larger cartilage defects are successfully treated by autologous membrane-induced chondrogenesis (AMIC) or by membrane-assisted autologous chondrocyte implantation (MACI).

CONCLUSION

Despite limitations of current cartilage repair strategies, such procedures can result in short- and mid-term clinical improvement of the patients. Further developments and clinical studies are necessary to improve the long-term outcome following cartilage repair.

Challenges in Fabrication of Tissue-Engineered Cartilage with Correct Cellular Colonization and Extracellular Matrix Assembly

A correct articular cartilage ultrastructure regarding its structural components and cellularity is important for appropriate performance of tissue-engineered articular cartilage. Various scaffold-based, as well as scaffold-free, culture models have been under development to manufacture functional cartilage tissue. Even decellularized tissues have been considered as a potential choice for cellular seeding and tissue fabrication. Pore size, interconnectivity, and functionalization of the scaffold architecture can be varied. Increased mechanical function requires a dense scaffold, which also easily restricts cellular access within the scaffold at seeding. High pore size enhances nutrient transport, while small pore size improves cellular interactions and scaffold resorption. In scaffold-free cultures, the cells assemble the tissue completely by themselves; in optimized cultures, they should be able to fabricate native-like tissue. Decellularized cartilage has a native ultrastructure, although it is a challenge to obtain proper cellular colonization during cell seeding. Bioprinting can, in principle, provide the tissue with correct cellularity and extracellular matrix content, although it is still an open question as to how the correct molecular interaction and structure of extracellular matrix could be achieved. These are challenges facing the ongoing efforts to manufacture optimal articular cartilage.

PPAR-δ Agonist With Mesenchymal Stem Cells Induces Type II Collagen-Producing Chondrocytes in Human Arthritic Synovial Fluid

Osteoarthritis (OA) is an inflammatory joint disease characterized by degeneration of articular cartilage within synovial joints. An estimated 27 million Americans suffer from OA, and the population is expected to reach 67 million in the United States by 2030. Thus, it is urgent to find an effective treatment for OA. Traditional OA treatments have no disease-modifying effect, while regenerative OA therapies such as autologous chondrocyte implantation show some promise. Nonetheless, current regenerative therapies do not overcome synovial inflammation that suppresses the differentiation of mesenchymal stem cells (MSCs) to chondrocytes and the expression of type II collagen, the major constituent of functional cartilage. We discovered a synergistic combination that overcame synovial inflammation to form type II collagen-producing chondrocytes. The combination consists of peroxisome proliferator–activated receptor (PPAR) δ agonist, human bone marrow (hBM)-derived MSCs, and hyaluronic acid (HA) gel. Interestingly, those individual components showed their own strong enhancing effects on chondrogenesis. GW0742, a PPAR-δ agonist, greatly enhanced MSC chondrogenesis and the expression of type II collagen and glycosaminoglycan (GAG) in hBM-MSC-derived chondrocytes. GW0742 also increased the expression of transforming growth factor β that enhances chondrogenesis and suppresses cartilage fibrillation, ossification, and inflammation. HA gel also increased MSC chondrogenesis and GAG production. However, neither GW0742 nor HA gel could enhance the formation of type II collagen-producing chondrocytes from hBM-MSCs within human OA synovial fluid. Our data demonstrated that the combination of hBM-MSCs, PPAR-δ agonist, and HA gel significantly enhanced the formation of type II collagen-producing chondrocytes within OA synovial fluid from 3 different donors. In other words, the novel combination of PPAR-δ agonist, hBM-MSCs, and HA gel can overcome synovial inflammation to form type II collagen cartilage within human OA synovial fluid. This novel articularly injectable formula could improve OA treatment in the future clinical application.

Terapias Celulares y Productos de Ingeniería de Tejidos para el Tratamiento de Lesiones Condrales de Rodilla

El cartílago articular es un tejido vulnerable a las lesiones de diferente etiología; siendo uno de los más afectados,  el cartílago de la rodilla. Aunque la mayoría de los tratamientos convencionales reducen los síntomas, generalmente conducen a la formación de fibrocartílago; el cual, posee características diferentes a las del cartílago hialino de las articulaciones.  Son pocas las aproximaciones terapéuticas que promueven el  reemplazo del tejido dañado por cartílago hialino funcional; las más exitosas son las denominadas terapias avanzadas, que aplican células y  productos de ingeniería de tejidos con el fin de estimular la regeneración del cartílago. La mayoría de ellas se basan en colocar soportes  hechos con biomateriales de diferente origen, que sembrados o no con células exógenas o endógenas, reemplazan al cartílago dañado y promueven su regeneración. Este  trabajo revisa algunas de las aproximaciones terapéuticas enfocadas en la regeneración del cartílago articular de rodilla; así como, los biomateriales más empleados en la elaboración de soportes para terapia celular e ingeniería de tejido cartilaginoso.

Three-Dimensional Seeding of Chondrocytes Encapsulated in Collagen Gel into PLLA Scaffolds

Tissue engineering approaches have been clinically tried to repair damaged articular cartilages. It is an essential step to uniformly seed chondrocytes into 3D scaffolds in order to reconstruct tissue-engineered cartilages in vitro, but the tissue engineering could not have been provided with efficient cell seeding methods. Type I collagen is clinically used and known as a cytocompatible material, having recognition sites for integrins. Collagen gel encapsulating chondrocytes has been tried for making regenerated cartilages, but it is found difficult to have the gel keep its original shape after long-term culture, because of shrinking. On the other hand, 3D scaffolds, either of a nonwoven structure or a sponge-like structure, involve difficulty in that chondrocytes could not be uniformly seeded, although they have adequate initial mechanical properties. In this study, by combining collagen gelation with a nonwoven PLLA scaffold, we achieved uniform cell seeding into the 3D scaffold. Bovine articular chondrocytes were mixed with type I collagen solution, and the solution was poured into the nonwoven PLLA scaffold (1.5 mm thick, f 15 mm). The collagen–chondrocyte mixture was made into gel at 37°C for 1 h. The 0.39% collagen mixture was viscous enough to prevent cells from precipitating during gelation. Almost all chondrocytes were able to be incorporated into the PLLA scaffolds by mixing with collagen solution and subsequently making into gel, while 30–40% of the chondrocytes seeded as a cell suspension were not trapped into the PLLA scaffolds. The method presented, where chondrocytes were mixed with collagen solution, and the mixture was incorporated into a 3D scaffold, then made into gel in the scaffold, could serve as an alternative for in vitro cartilage regeneration, also simultaneously having the advantages of both materials.

Craniofacial Tissue Engineering

There is substantial need for the replacement of tissues in the craniofacial complex due to congenital defects, disease, and injury. The field of tissue engineering, through the application of engineering and biological principles, has the potential to create functional replacements for damaged or pathologic tissues. Three main approaches to tissue engineering have been pursued: conduction, induction by bioactive factors, and cell transplantation. These approaches will be reviewed as they have been applied to key tissues in the craniofacial region. While many obstacles must still be overcome prior to the successful clinical restoration of tissues such as skeletal muscle and the salivary glands, significant progress has been achieved in the development of several tissue equivalents, including skin, bone, and cartilage. The combined technologies of gene therapy and drug delivery with cell transplantation will continue to increase treatment options for craniofacial cosmetic and functional restoration.

Surgical treatment of the neglected achilles tendon rupture with Hyalonect

BACKGROUND

The purpose of this study was to report the management and outcomes of ten patients with chronic Achilles tendon rupture treated with a turndown gastrocnemius-soleus fascial flap wrapped with a surgical mesh (Hyalonect).

METHODS

Ten men with neglected Achilles tendon rupture were treated with a centrally based turndown gastrocnemius fascial flap wrapped with Hyalonect. Hyalonect is a knitted mesh composed of HYAFF, a benzyl ester of hyaluronic acid. The Achilles tendon ruptures were diagnosed more than 1 month after injury. The mean patient age was 41 years. All of the patients had weakness of active plantarflexion. The mean preoperative American Orthopaedic Foot and Ankle Society score was 64.8.

RESULTS

The functional outcome was excellent. The mean American Orthopaedic Foot and Ankle Society score was 97.8 at the latest follow-up. There were significant differences between the preoperative and postoperative scores. Ankle range of motion was similar in both ankles. Neither rerupture nor major complication, particularly of wound healing, was observed.

CONCLUSIONS

For patients with chronic Achilles tendon rupture with a rupture gap of at least 5 cm, surgical repair using a single turndown fascial flap covered with Hyalonect achieved excellent outcomes.

Treatment of osteochondral lesions of the talus in athletes: what is the evidence?

PURPOSE

ankle injuries make up 15% of all sports injuries and osteochondral lesions of the talus (OLTs) are an increasingly frequent problem in active patients. There exist no widely shared guidelines on OLT treatment in the athletic population. The aim of this paper is to review all the existing literature evidence on the surgical treatment of OLTs in athletes, in order to determine the current state of the art in this specific population, underlining both the limits and the potential of the strategies used.

METHODS

a systematic review of the literature was performed focusing on the different types of surgical treatment used for OLTs in athletes. The screening process and analysis were performed separately by two independent researchers. The inclusion criteria for relevant articles were: clinical reports of any level of evidence, written in English, with no time limitation, or clinical reports describing the treatment of OLTs in the athletic population.

RESULTS

with the consensus of the two observers, relevant data were then extracted and collected in a single database to be analyzed for the purposes of the present manuscript. At the end of the process, 16 papers met the selection criteria. These papers report a total of 642 athletic patients with OCTs.

CONCLUSIONS

the ideal treatment for cartilage lesions in athletes is a controversial topic, due to the need for an early return to sports, especially in elite players; this need leads to extensive use of microfractures in this population, despite the poor quality of repair associated with this technique. None of the surgical strategies described in this paper seems to be superior to the others.

LEVEL OF EVIDENCE

systematic review of level IV studies, level IV.

Cell-based tissue engineering strategies used in the clinical repair of articular cartilage

One of the most important issues facing cartilage tissue engineering is the inability to move technologies into the clinic. Despite the multitude of current research in the field, it is known that 90% of new drugs that advance past animal studies fail clinical trials. The objective of this review is to provide readers with an understanding of the scientific details of tissue engineered cartilage products that have demonstrated a certain level of efficacy in humans, so that newer technologies may be developed upon this foundation. Compared to existing treatments, such as microfracture or autologous chondrocyte implantation, a tissue engineered product can potentially provide more consistent clinical results in forming hyaline repair tissue and in filling the entirety of the defect. The various tissue engineering strategies (e.g., cell expansion, scaffold material, media formulations, biomimetic stimuli, etc.) used in forming these products, as collected from published literature, company websites, and relevant patents, are critically discussed. The authors note that many details about these products remain proprietary, not all information is made public, and that advancements to the products are continuously made. Nevertheless, by understanding the design and production processes of these emerging technologies, one can gain tremendous insight into how to best use them and also how to design the next generation of tissue engineered cartilage products.

Cell-based tissue engineering strategies used in the clinical repair of articular cartilage

One of the most important issues facing cartilage tissue engineering is the inability to move technologies into the clinic. Despite the multitude of current research in the field, it is known that 90% of new drugs that advance past animal studies fail clinical trials. The objective of this review is to provide readers with an understanding of the scientific details of tissue engineered cartilage products that have demonstrated a certain level of efficacy in humans, so that newer technologies may be developed upon this foundation. Compared to existing treatments, such as microfracture or autologous chondrocyte implantation, a tissue engineered product can potentially provide more consistent clinical results in forming hyaline repair tissue and in filling the entirety of the defect. The various tissue engineering strategies (e.g., cell expansion, scaffold material, media formulations, biomimetic stimuli, etc.) used in forming these products, as collected from published literature, company websites, and relevant patents, are critically discussed. The authors note that many details about these products remain proprietary, not all information is made public, and that advancements to the products are continuously made. Nevertheless, by understanding the design and production processes of these emerging technologies, one can gain tremendous insight into how to best use them and also how to design the next generation of tissue engineered cartilage products.

Nanofibrous spongy microspheres enhance odontogenic differentiation of human dental pulp stem cells

Dentin regeneration is challenging due to its complicated anatomical structure and the shortage of odontoblasts. In this study, a novel injectable cell carrier, nanofibrous spongy microspheres (NF-SMS), is developed for dentin regeneration. Biodegradable and biocompatible poly(l-lactic acid)-block-poly(l-lysine) are synthesized and fabricated into NF-SMS using self-assembly and thermally induced phase separation techniques. It is hypothesized that NF-SMS with interconnected pores and nanofibers can enhance the proliferation and odontogenic differentiation of human dental pulp stem cells (hDPSCs), compared to nanofibrous microspheres (NF-MS) without pore structure and conventional solid microspheres (S-MS) with neither nanofibers nor pore structure. During the first 9 d in culture, hDPSCs proliferate significantly faster on NF-SMS than on NF-MS or S-MS (p < 0.05). Following in vitro odontogenic induction, all the examined odontogenic genes (alkaline phosphatase content, osteocalcin, bone sialoprotein, collagen 1, dentin sialophosphoprotein (DSPP)), calcium content, and DSPP protein content are found significantly higher in the NF-SMS group than in the control groups. Furthermore, 6 weeks after subcutaneous injection of hDPSCs and microspheres into nude mice, histological analysis shows that NF-SMS support superior dentin-like tissue formation compared to NF-MS or S-MS. Taken together, NF-SMS have great potential as an injectable cell carrier for dentin regeneration.

New adipose tissue formation by human adipose-derived stem cells with hyaluronic acid gel in immunodeficient mice

BACKGROUND

Currently available injectable fillers have demonstrated limited durability. This report proposes the in vitro culture of human adipose-derived stem cells (hASCs) on hyaluronic acid (HA) gel for in vivo growth of de novo adipose tissue.

METHODS

For in vitro studies, hASCs were isolated from human adipose tissue and were confirmed by multi-lineage differentiation and flow cytometry. hASCs were cultured on HA gel. The effectiveness of cell attachment and proliferation on HA gel was surveyed by inverted light microscopy. For in vivo studies, HA gel containing hASCs, hASCs without HA gel, HA gel alone were allocated and subcutaneously injected into the subcutaneous pocket in the back of nude mice (n=6) in each group. At eight weeks post-injection, the implants were harvested for histological examination by hematoxylin and eosin (H&E) stain, Oil-Red O stain and immunohistochemical staining. The human-specific Alu gene was examined.

RESULTS

hASCs were well attachment and proliferation on the HA gel. In vivo grafts showed well-organized new adipose tissue on the HA gel by histologic examination and Oil-Red O stain. Analysis of neo-adipose tissues by PCR revealed the presence of the Alu gene. This study demonstrated not only the successful culture of hASCs on HA gel, but also their full proliferation and differentiation into adipose tissue.

CONCLUSIONS

The efficacy of injected filler could be permanent since the reduction of the volume of the HA gel after bioabsorption could be replaced by new adipose tissue generated by hASCs. This is a promising approach for developing long lasting soft tissue filler.

Hyaluronic acid effect on adipose-derived stem cells. Biological in vitro evaluation

OBJECTIVES

To evaluate the in vitro effects of hyaluronic acid (HA) on adipose-derived stem cells (ASC) in order to consider the possibility of their combined used in the treatment of knee arthrosis.

MATERIAL AND METHODS

The ASC cells were grown both in the presence and absence of AH, and several studies were carried out: proliferation (WST8) and cell viability studies (Alamar Blue® and Trypan Blue), possible chondrogenic differentiation (collagen type 2 expression) by RT-PCR, AH receptor expression (CD44) by flow cytometry and RT-QPCR, and expression of inflammatory and anti-inflammatory factors (IL-6, TGFß, IL-10) by RT-QPCR.

RESULTS

The number of ASC significantly increased after 7 days with HA (158±39%, p <0.05). Additionally, the cell viability of the ASC treated with HA after 1, 3, 5 and 7 days was similar to that of the control cells, being considered non-toxic. There were no changes observed in the expression of CD44 and chondrogenic differentiation. TGFß expression was not modified after AH treatment, but there was a 4-fold decrease in IL-6 expression and IL-10 expression increased up to 2-fold compared to control cells.

CONCLUSIONS

Hyaluronic acid favours ASC proliferation without causing cellular toxicity, and inducing an anti-inflammatory profile in these cells. Hyaluronic acid appears to be a suitable vehicle for the intra-articular administration of mesenchymal stem cells.

Clinical efficacy of a spray containing hyaluronic Acid and dexpanthenol after surgery in the nasal cavity (septoplasty, simple ethmoid sinus surgery, and turbinate surgery)

Background. This prospective, controlled, parallel-group observational study investigated the efficacy of a spray containing hyaluronic acid and dexpanthenol to optimise regular treatment after nasal cavity surgery in 49 patients with chronic rhinosinusitis. Methods. The control group received standard therapy. Mucosal regeneration was determined using rhinoscopy sum score (RSS). Pre- and postoperative nasal patency was tested using anterior rhinomanometry. The participants were questioned about their symptoms. Results. Regarding all RSS parameters (dryness, dried nasal mucus, fibrin deposition, and obstruction), mucosal regeneration achieved good final results in both groups, tending to a better improvement through the spray application, without statistically significant differences during the whole assessment period, the mean values being 7.04, 5.00, 3.66, and 3.00 (intervention group) and 7.09, 5.14, 4.36, and 3.33 (control group). No statistically significant benefit was identified for nasal breathing, foreign body sensation, and average rhinomanometric volume flow, which improved by 12.31% (control group) and 11.24% (nasal spray group). Conclusion. The investigational product may have additional benefit on postoperative mucosal regeneration compared to standard cleaning procedures alone. However, no statistically significant advantage could be observed in this observational study. Double-blind, controlled studies with larger populations will be necessary to evaluate the efficacy of this treatment modality.

Autologous Matrix-Induced Chondrogenesis in the Knee: A Review

OBJECTIVE

Autologous matrix-induced chondrogenesis (AMIC) is a 1-step cartilage restoration technique that combines microfracture with the use of an exogenous scaffold. This matrix covers and mechanically stabilizes the clot. There have been an increasing number of studies performed related to the AMIC technique and an update of its use and results is warranted.

DESIGN AND METHODS

Using the PubMed database, a literature search was performed using the terms "AMIC" or "Autologous Matrix Induced Chondrogenesis." A total of 19 basic science and clinical articles were identified.

RESULTS

Ten studies that were published on the use of AMIC for knee chondral defects were identified and the results of 219 patients were analyzed. The improvements in Knee Injury and Osteoarthritis Outcome Score, International Knee Documentation Committee Subjective, Lysholm and Tegner scores at 2 years were comparable to the published results from autologous chondrocyte implantation (ACI) and matrix ACI techniques for cartilage repair.

CONCLUSIONS

Our systematic review of the current state of the AMIC technique suggests that it is a promising 1-stage cartilage repair technique. The short-term clinical outcomes and magnetic resonance imaging results are comparable to other cell-based methods. Further studies with AMIC in randomized studies versus other repair techniques such as ACI are needed in the future.

Improvement of PHBV scaffolds with bioglass for cartilage tissue engineering

Polymer scaffold systems consisting of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) have proven to be possible matrices for the three-dimensional growth of chondrocyte cultures. However, the engineered cartilage grown on these PHBV scaffolds is currently unsatisfactory for clinical applications due to PHBV’s poor hydrophilicity, resulting in inadequate thickness and poor biomechanical properties of the engineered cartilage. It has been reported that the incorporation of Bioglass (BG) into PHBV can improve the hydrophilicity of the composites. In this study, we compared the effects of PHBV scaffolds and PHBV/BG composite scaffolds on the properties of engineered cartilage in vivo. Rabbit articular chondrocytes were seeded into PHBV scaffolds and PHBV/BG scaffolds. Short-term in vitro culture followed by long-term in vivo transplantation was performed to evaluate the difference in cartilage regeneration between the cartilage layers grown on PHBV and PHBV/BG scaffolds. The results show that the incorporation of BG into PHBV efficiently improved both the hydrophilicity of the composites and the percentage of adhered cells and promoted cell migration into the inner part the constructs. With prolonged incubation time in vivo, the chondrocyte-scaffold constructs in the PHBV/BG group formed thicker cartilage-like tissue with better biomechanical properties and a higher cartilage matrix content than the constructs in the PHBV/BG group. These results indicate that PHBV/BG scaffolds can be used to prepare better engineered cartilage than pure PHBV.

One-step bone marrow-derived cell transplantation in talarosteochondral lesions: mid-term results

PURPOSE

to verify the capability of scaffold-supported bone marrow-derived cells to be used in the repair of osteochondral lesions of the talus.

METHODS

using a device to concentrate bone marrow-derived cells, a scaffold (collagen powder or hyaluronic acid membrane) for cell support and platelet gel, a one-step arthroscopic technique was developed for cartilage repair. In a prospective clinical study, we investigated the ability of this technique to repair talar osteochondral lesions in 64 patients. The mean follow-up was 53 months. Clinical results were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) scale score. We also considered the influence of scaffold type, lesion area, previous surgery, and lesion depth.

RESULTS

the mean preoperative AOFAS scale score was 65.2 ± 13.9. The clinical results peaked at 24 months, before declining gradually to settle at a score of around 80 at the maximum follow-up of 72 months.

CONCLUSIONS

the use of bone marrow-derived cells supported by scaffolds to repair osteochondral lesions of the talus resulted in significant clinical improvement, which was maintained over time.

LEVEL OF EVIDENCE

level IV, therapeutic case series.

Applications and emerging trends of hyaluronic acid in tissue engineering, as a dermal filler and in osteoarthritis treatment

Hyaluronic acid (HA) is a naturally occurring biodegradable polymer with a variety of applications in medicine, including scaffolding for tissue engineering, dermatological fillers and viscosupplementation for osteoarthritis treatment. HA is available in most connective tissues in body fluids such as synovial fluid and the vitreous humor of the eye. HA is responsible for several structural properties of tissues as a component of extracellular matrix and is involved in cellular signaling. Degradation of HA is a stepwise process that can occur via enzymatic or non-enzymatic reactions. A reduction in HA mass or molecular weight via degradation or slowing of synthesis affects physical and chemical properties such as tissue volume, viscosity and elasticity. This review addresses the distribution, turnover and tissue-specific properties of HA. This information is used as the context for considering recent products and strategies for modifying the viscoelastic properties of HA in tissue engineering, as a dermal filler and in osteoarthritis treatment.

Human Ng2+ adipose stem cells loaded in vivo on a new crosslinked hyaluronic acid-Lys scaffold fabricate a skeletal muscle tissue

Mesenchymal stem cell (MSC) therapy holds promise for treating diseases and tissue repair. Regeneration of skeletal muscle tissue that is lost during pathological muscle degeneration or after injuries is sustained by the production of new myofibers. Human Adipose stem cells (ASCs) have been reported to regenerate muscle fibers and reconstitute the pericytic cell pool after myogenic differentiation in vitro. Our aim was to evaluate the differentiation potential of constructs made from a new cross-linked hyaluronic acid (XHA) scaffold on which different sorted subpopulations of ASCs were loaded. Thirty days after engraftment in mice, we found that NG2(+) ASCs underwent a complete myogenic differentiation, fabricating a human skeletal muscle tissue, while NG2(-) ASCs merely formed a human adipose tissue. Myogenic differentiation was confirmed by the expression of MyoD, MF20, laminin, and lamin A/C by immunofluorescence and/or RT-PCR. In contrast, adipose differentiation was confirmed by the expression of adiponectin, Glut-4, and PPAR-γ. Both tissues formed expressed Class I HLA, confirming their human origin and excluding any contamination by murine cells. In conclusion, our study provides novel evidence that NG2(+) ASCs loaded on XHA scaffolds are able to fabricate a human skeletal muscle tissue in vivo without the need of a myogenic pre-differentiation step in vitro. We emphasize the translational significance of our findings for human skeletal muscle regeneration.

One-step repair in talar osteochondral lesions: 4-year clinical results and t2-mapping capability in outcome prediction

BACKGROUND

A recent one-step arthroscopic technique based on bone marrow-derived cell transplantation has achieved good results in repairing osteochondral lesions of the talus (OLTs), overcoming some of the drawbacks of older techniques.

PURPOSE

To report the results after 4 years of a series of patients who underwent a one-step repair of osteochondral lesions of the talar dome, as well as the capability of magnetic resonance imaging (MRI) using a T2-mapping sequence to predict the clinical outcome.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Forty-nine patients (age [mean ± SD], 28.08 ± 9.51 y) underwent a one-step repair of OLTs. Patients were evaluated clinically by American Orthopaedic Foot and Ankle Society (AOFAS) scores and radiographs and underwent MRI preoperatively and during postoperative follow-ups at predetermined times. In all patients, the cells were harvested from the iliac crest, concentrated, and loaded on a scaffold that was implanted arthroscopically.

RESULTS

The overall AOFAS score (mean ± SD) improved from 63.73 ± 14.13 preoperatively to 82.19 ± 17.04 at 48 ± 6.1 months (P < .0005), with best results at the 24-month follow-up. A significant decrease in the clinical score was observed between 24 and 36 months postoperatively (P = .001) and between 24 and 48 months (P < .005). The T2-mapping analysis showed regenerated tissue with T2 values of 35 to 45 milliseconds, similar to hyaline cartilage, in a mean of 78% ± 16% of the repaired lesion area. The time between the occurrence of trauma and surgery was found to negatively affect the clinical outcome at the latest follow-up; patient's age and lesion size influenced the early clinical results but did not affect the outcome at final follow-up. The stability of clinical results over time and the percentage of tissue with values similar to hyaline cartilage evidenced by MRI T2 mapping showed a tendency to correlate at the last follow-up (r = 0.497, P = .06).

CONCLUSION

One-step repair of OLTs had good clinical results that were durable over time, even though there was a slight decrease in AOFAS score at the latest follow-up. The quality of the regenerated tissue detected by MRI T2 mapping directly correlated with the clinical results.

Scaffolds for cartilage repair of the ankle joint: The impact on surgical practice

BACKGROUND

Ideal management of osteochondral lesions in the ankle joint is still theme of debate. Scaffold-based repair is emerging as a new approach for regenerative treatment.

METHODS

Articles published in PubMed from 2000 to January 2012 addressing cartilage scaffold-based treatment were identified, including levels I-IV evidence clinical trials with measures of functional, clinical or imaging outcome.

RESULTS

The analysis showed a progressively increasing number of articles from 2000. The number of selected papers was 19:15 focusing on two-step and 4 on one-step procedures; no randomized studies, 3 comparative studies, 11 case series and 5 case reports were identified.

CONCLUSIONS

Regenerative surgical approach with scaffold-based procedures is emerging as a potential therapeutic option for the treatment of chondral lesions of the ankle. One step treatments simplify the procedure and the results reported are very close to the previous techniques. However, well-designed studies are lacking, and randomized long-term trials are necessary to confirm the potential of these techniques.

LEVEL OF EVIDENCE

Review - IV.

Adipose tissue regeneration: a state of the art

Adipose tissue pathologies and defects have always represented a reconstructive challenge for plastic surgeons. In more recent years, several allogenic and alloplastic materials have been developed and used as fillers for soft tissue defects. However, their clinical use has been limited by further documented complications, such as foreign-body reactions potentially affecting function, degradation over time, and the risk for immunogenicity. Tissue-engineering strategies are thus being investigated to develop methods for generating adipose tissue. This paper will discuss the current state of the art in adipose tissue engineering techniques, exploring the biomaterials used, stem cells application, culture strategies, and current regulatory framework that are in use are here described and discussed.