Cartilage Repair Using Composites of Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells and Hyaluronic Acid Hydrogel in a Minipig Model

Bibliometric analysis of organoids in regenerative medicine-related research worldwide over two decades (2002-2022)

Aim: This study aimed to evaluate the trends in organoid culture research within the field of regenerative medicine from 2002 to 2022. Methods: The worldwide distribution of organoid research in regenerative medicine articles indexed in the Scopus database was analyzed. Result: A total of 840 documents were analyzed, averaging 42 publications annually. The USA (n = 296) led in publications, followed by China (n = 127), Japan (n = 91) and the UK (n = 75). Since 2011, research has surged, particularly in China, which emerged as a prominent center. Conclusion: The findings highlight significant growth in organoid research, promising future organ transplantation. Research trends integrate tissue engineering, gene modification and induced pluripotent stem cell technologies, reflecting a move toward personalized medicine.

Protecting the regenerative environment: selecting the optimal delivery vehicle for cartilage repair-a narrative review

Focal cartilage defects are common in youth and older adults, cause significant morbidity and constitute a major risk factor for developing osteoarthritis (OA). OA is the most common musculoskeletal (MSK) disease worldwide, resulting in pain, stiffness, loss of function, and is currently irreversible. Research into the optimal regenerative approach and methods in the setting of either focal cartilage defects and/or OA holds to the ideal of resolving both diseases. The two fundamentals required for cartilage regenerative treatment are 1) the biological element contributing to the regeneration (e.g., direct application of stem cells, or of an exogenous secretome), and 2) the vehicle by which the biological element is suspended and delivered. The vehicle provides support to the regenerative process by providing a protective environment, a structure that allows cell adherence and migration, and a source of growth and regenerative factors that can activate and sustain regeneration. Models of cartilage diseases include osteochondral defect (OCD) (which usually involve one focal lesion), or OA (which involves a more diffuse articular cartilage loss). Given the differing nature of these models, the optimal regenerative strategy to treat different cartilage diseases may not be universal. This could potentially impact the translatability of a successful approach in one condition to that of the other. An analogy would be the repair of a pothole (OCD) versus repaving the entire road (OA). In this narrative review, we explore the existing literature evaluating cartilage regeneration approaches for OCD and OA in animal then in human studies and the vehicles used for each of these two conditions. We then highlight strengths and challenges faced by the different approaches presented and discuss what might constitute the optimal cartilage regenerative delivery vehicle for clinical cartilage regeneration.

Kartogenin delivery systems for biomedical therapeutics and regenerative medicine

Kartogenin, a small and heterocyclic molecule, has emerged as a promising therapeutic agent for incorporation into biomaterials, owing to its unique physicochemical and biological properties. It holds potential for the regeneration of cartilage-related tissues in various common conditions and injuries. Achieving sustained release of kartogenin through appropriate formulation and efficient delivery systems is crucial for modulating cell behavior and tissue function. This review provides an overview of cutting-edge kartogenin-functionalized biomaterials, with a primarily focus on their design, structure, functions, and applications in regenerative medicine. Initially, we discuss the physicochemical properties and biological functions of kartogenin, summarizing the underlying molecular mechanisms. Subsequently, we delve into recent advancements in nanoscale and macroscopic materials for the carriage and delivery of kartogenin. Lastly, we address the opportunities and challenges presented by current biomaterial developments and explore the prospects for their application in tissue regeneration. We aim to enhance the generation of insightful ideas for the development of kartogenin delivery materials in the field of biomedical therapeutics and regenerative medicine by providing a comprehensive understanding of common preparation methods.

Comparison of compositional MRI techniques to quantify the regenerative potential of articular cartilage: a preclinical minipig model after osteochondral defect treatments with autologous mesenchymal stromal cells and unseeded scaffolds

Background

The field of orthopedics seeks effective, safer methods for evaluating articular cartilage regeneration. Despite various treatment innovations, non-invasive, contrast-free full quantitative assessments of hyaline articular cartilage's regenerative potential using compositional magnetic resonance (MR) sequences remain challenging. In this context, our aim was to investigate the effectiveness of different MR sequences for quantitative assessment of cartilage and to compare them with the current gold standard delayed gadolinium-enhanced MR imaging of cartilage (dGEMRIC) measurements.

Methods

We employed ex vivo imaging in a preclinical minipig model to assess knee cartilage regeneration. Standardized osteochondral defects were drilled in the proximal femur of the specimens (n=14), which were divided into four groups. Porcine collagen scaffolds seeded with autologous adipose-derived stromal cells (ASC), autologous bone marrow stromal cells (BMSC), and unseeded scaffolds (US) were implanted in femoral defects. Furthermore, there was a defect group which received no treatment. After 6 months, the specimens were examined using different compositional MR methods, including the gold standard dGEMRIC as well as T1, T2, T2*, and T1ρ techniques. The statistical evaluation involved comparing the defect region with the uninjured tibia and femur cartilage layers and all measurements were performed on a clinical 3T MR Scanner.

Results

In the untreated defect group, we observed significant differences in the defect region, with dGEMRIC values significantly lower (404.86±64.2 ms, P=0.018) and T2 times significantly higher (44.24±2.75 ms, P<0.001). Contrastingly, in all three treatment groups (ASC, BMSC, US), there were no significant differences among the three regions in the dGEMRIC sequence, suggesting successful cartilage regeneration. However, T1, T2*, and T1ρ sequences failed to detect such differences, highlighting their lower sensitivity for cartilage regeneration.

Conclusions

As expected, dGEMRIC is well suited for monitoring cartilage regeneration. Interestingly, T2 imaging also proved to be a reliable cartilage imaging technique and thus offers a contrast agent-free alternative to the former gold standard for subsequent in vivo studies investigating the cartilage regeneration potential of different treatment modalities.

Macromolecule-based hydrogels nanoarchitectonics with mesenchymal stem cells for regenerative medicine: A review

The role of regenerative medicine in clinical therapies is becoming increasingly vital. Under specific conditions, mesenchymal stem cells (MSCs) are capable of differentiating into mesoblastema (i.e., adipocytes, chondrocytes, and osteocytes) and other embryonic lineages. Their application in regenerative medicine has attracted a great deal of interest among researchers. To maximize the potential applications of MSCs, materials science could provide natural extracellular matrices and provide an effective means to understand the various mechanisms of differentiation for the growth of MSCs. Pharmaceutical fields are represented among the research on biomaterials by macromolecule-based hydrogel nanoarchitectonics. Various biomaterials have been used to prepare hydrogels with their unique chemical and physical properties to provide a controlled microenvironment for the culture of MSCs, laying the groundwork for future practical applications in regenerative medicine. This article currently describes and summarizes the sources, characteristics, and clinical trials of MSCs. In addition, it describes the differentiation of MSCs in various macromolecule-based hydrogel nanoarchitectonics and highlights the preclinical studies of MSCs-loaded hydrogel materials in regenerative medicine conducted over the past few years. Finally, the challenges and prospects of MSC-loaded hydrogels are discussed, and the future development of macromolecule-based hydrogel nanoarchitectonics is outlined by comparing the current literature.

OUP accepted manuscript

Although successful short-term results of the intra-articular injection of mesenchymal stem cells (MSCs) for the conservative treatment of knee osteoarthritis (OA) have been reported, the mid-term results of the injection of adipose-derived (AD) MSCs remains unknown. We assessed the mid-term safety and efficacy of the intra-articular injection of ADMSCs in patients with knee OA. Eleven patients with knee OA were prospectively enrolled and underwent serial evaluations during a 5-year follow-up of a single intra-articular injection of autologous high-dose (1.0 × 10⁸) ADMSCs. The safety profiles were assessed using the World Health Organization Common Toxicity Criteria. The clinical evaluations included visual analog scale (VAS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores for pain and function, respectively. The radiologic evaluations included chondral defect area and whole-organ magnetic resonance imaging scores (WORMS) by serial magnetic resonance imaging (MRI). Hip-knee-ankle axis (HKAA) and Kellgren-Lawrence (K-L) grades were assessed on simple radiographs. No treatment-related adverse events occurred during the 5-year follow-up. Both VAS and total WOMAC scores improved significantly at 6 months after the injection and until the latest follow-up. Total WORMS was significantly improved until 3 years after the injection. However, the chondral defect size on MRI or other radiologic evaluations did not change significantly. A single intra-articular injection of autologous, high-dose ADMSCs provided safe and clinical improvement without radiologic aggravation for 5 years. Furthermore, structural changes in the osteoarthritic knee showed significant improvement up to 3 years, suggesting a possible option for disease-modifying outpatient treatment for patients with knee OA.

Recent advances of 3D hydrogel culture systems for mesenchymal stem cell-based therapy and cell behavior regulation

Mesenchymal stem cells (MSCs) have been increasingly recognized as resources for disease treatments and regenerative medicine. Meanwhile, the unique chemical and physical properties of hydrogels provide innate advantages to achieve...

Human Umbilical Mesenchymal Stromal Cells Mixed with Hyaluronan Transplantation Decreased Cartilage Destruction in a Rabbit Osteoarthritis Model

Osteoarthritis (OA), the most common type of arthritis, causes pain in joints and disability. Due to the absence of ideal effective medication, stem cell transplantation emerges as a new hope for OA therapy. This study is aimed at evaluating the capability of human umbilical cord mesenchymal stromal cells (HUCMSCs) mixed with hyaluronan (HA) to treat osteoarthritis in a rabbit model. Differentiation capability of HUCMSCs, magnetic resonance image examination, and immunohistochemistry of the cartilage after transplantation of HUCMSCs mixed with HA in a rabbit OA model were explored. HUCMSCs exhibited typical mesenchymal stromal cell (MSC) characteristics, including spindle-shaped morphology, surface marker expressions (positive for human leukocyte antigen- (HLA-) ABC, CD44, CD73, CD90, and CD105; negative for HLA-DR, CD34, and CD45), and trilineage differentiation (chondrogenesis, adipogenesis, and osteogenesis). The gene expression of SOX9, type II collagen, and aggrecan in the HUCMSC-derived chondrocytes mixed with HA was increased after in vitro chondrogenesis compared with HUCMSCs. A gross and histological significant improvement in hyaline cartilage destruction after HUCMSCs mixed with HA was noted in the animal model compared to the OA knees. The International Cartilage Repair Society histological score and Safranin O staining were significantly higher for the treated knees than the control knees (p < 0.05). Moreover, the expression of MMP13 was significantly decreased in the treated knees than in the OA knees. In conclusion, HUCMSCs mixed with HA in vitro and in vivo might attenuate the cartilage destruction in osteoarthritis. Our study provided evidence for future clinical trials.

The Therapeutic Potential of Mesenchymal Stromal Cells for Regenerative Medicine: Current Knowledge and Future Understandings

In recent decades, research on the therapeutic potential of progenitor cells has advanced considerably. Among progenitor cells, mesenchymal stromal cells (MSCs) have attracted significant interest and have proven to be a promising tool for regenerative medicine. MSCs are isolated from various anatomical sites, including bone marrow, adipose tissue, and umbilical cord. Advances in separation, culture, and expansion techniques for MSCs have enabled their large-scale therapeutic application. This progress accompanied by the rapid improvement of transplantation practices has enhanced the utilization of MSCs in regenerative medicine. During tissue healing, MSCs may exhibit several therapeutic functions to support the repair and regeneration of injured tissue. The process underlying these effects likely involves the migration and homing of MSCs, as well as their immunotropic functions. The direct differentiation of MSCs as a cell replacement therapeutic mechanism is discussed. The fate and behavior of MSCs are further regulated by their microenvironment, which may consequently influence their repair potential. A paracrine pathway based on the release of different messengers, including regulatory factors, chemokines, cytokines, growth factors, and nucleic acids that can be secreted or packaged into extracellular vesicles, is also implicated in the therapeutic properties of MSCs. In this review, we will discuss relevant outcomes regarding the properties and roles of MSCs during tissue repair and regeneration. We will critically examine the influence of the local microenvironment, especially immunological and inflammatory signals, as well as the mechanisms underlying these therapeutic effects. Importantly, we will describe the interactions of local progenitor and immune cells with MSCs and their modulation during tissue injury. We will also highlight the crucial role of paracrine pathways, including the role of extracellular vesicles, in this healing process. Moreover, we will discuss the therapeutic potential of MSCs and MSC-derived extracellular vesicles in the treatment of COVID-19 (coronavirus disease 2019) patients. Overall, this review will provide a better understanding of MSC-based therapies as a novel immunoregenerative strategy.

Umbilical cord mesenchymal stem/stromal cells potential to treat organ disorders; an emerging strategy

Currently, mesenchymal stem/stromal cells (MSCs) have attracted growing attention in the context of cell-based therapy in regenerative medicine. Following the first successful procurement of human MSCs from bone marrow (BM), these cells isolation has been conducted from various origins, in particular, the umbilical cord (UC). Umbilical cord-derived mesenchymal stem/stromal cells (UC-MSCs) can be acquired by a non-invasive plan and simply cultured, and thereby signifies their superiority over MSCs derived from other sources for medical purposes. Due to their unique attributes, including self-renewal, multipotency, and accessibility concomitant with their immunosuppressive competence and lower ethical concerns, UC-MSCs therapy is described as encouraging therapeutic options in cell-based therapies. Regardless of their unique aptitude to adjust inflammatory response during tissue recovery and delivering solid milieu for tissue restoration, UC-MSCs can be differentiated into a diverse spectrum of adult cells (e.g., osteoblast, chondrocyte, type II alveolar, hepatocyte, and cardiomyocyte). Interestingly, they demonstrate a prolonged survival and longer telomeres compared with MSCs derived from other sources, suggesting that UC-MSCs are desired source to use in regenerative medicine. In the present review, we deliver a brief review of UC-MSCs isolation, expansion concomitantly with immunosuppressive activities, and try to collect and discuss recent pre-clinical and clinical researches based on the use of UC-MSCs in regenerative medicine, focusing on with special focus on in vivo researches.

Human Periodontal Ligament Stem Cells Transplanted with Nanohydroxyapatite/Chitosan/Gelatin 3D Porous Scaffolds Promote Jaw Bone Regeneration in Swine

Dental-tissue-derived stem cells have been used for tissue engineering owing to their ease of isolation and efficacy in in vitro and in vivo proliferation and differentiation. Nanohydroxyapatite/chitosan/gelatin (nHA/CG) three-dimensional porous scaffolds are promising for bone tissue engineering, especially jaw bone regeneration, because of their structural and functional similarity to natural bone. In our previous study, the efficiency of scaffolds with stem cell complexes in osteogenesis was confirmed in vivo in immunocompromised mice. However, studies on the bone regeneration efficiency of stem cell-seeded nHA/CG scaffolds using large animal jaw bone defect models have not been conducted. This study evaluated the bone regeneration potential of the nHA/CG scaffolds with transplanted human periodontal ligament stem cells (hPDLSCs) in critical-sized jaw bone defects in minipigs. The hPDLSCs isolated from periodontal ligaments of discarded teeth (postorthodontic purposes) were seeded onto the nHA/CG scaffolds. The scaffold was successfully synthesized according to our previous studies. Forty-eight critical-sized jaw bone defects were created in 12 minipigs. The defects were randomly assigned to one of three groups [scaffolds with seeded hPDLSCs (hPDLSCs/nHA/CG), only scaffold (nHA/CG), and a negative control group, ie, no cells and scaffolds implanted into defects] to investigate jaw bone regeneration. The bone regeneration capacities of the three groups were assessed for up to 12 weeks. The results showed that the hPDLSCs adhered well to the nHA/CG scaffold in vitro, and the cell-nHA/CG composites significantly increased new bone formation and generated large bones with normal architectures and vascularization in vivo compared to the nHA/CG and control groups. Immunohistochemistry staining showed that runt-related transcription factor 2 (Runx2) was highly expressed in the bone marrow formed in the hPDLSCs/nHA/CG group. This study provides strong evidence for future clinical applications of the nHA/CG scaffolds transplanted with hPDLSCs to regenerate the bone in large jaw bone defects.

Transplantation of Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells Improves Cartilage Repair in a Rabbit Model

The aim of this study was to investigate the therapeutic efficacy and safety of transplanting human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) in the treatment of cartilage injury. First, the articular cartilage defect model in rabbits was constructed. Then, the identified hUCB-MSCs and rabbit bone marrow stem cells (rBM-MSCs) were transplanted into the bone defect, respectively, and the cartilage repair effect was observed by hematoxylin-eosin (HE) staining and immunohistochemistry. Besides, the glycosaminoglycan (GAG) content and biomechanics of the restoration area were also evaluated. In our study, hUCB-MSCs and rBM-MSCs exhibited typical MSC characteristics, with positive expressions of CD73, CD105, and CD90 and negative for CD45, CD34, CD14, and HLA-DR. After the transplantation of hUCB-MSCs and rBM-MSCs, the overall quality of cartilage tissue was significantly improved, and the recipients did not show significant side effects in general. However, the expression of matrix metalloproteinase-13 (MMP-13) in the de novo tissues of the hUCB-MSCs and rBM-MSCs groups was both increased, indicating that the novel tissues may have some potential osteoarthritic changes. In conclusion, our results suggest the therapeutic effect of hUCB-MSCs transplantation in cartilage regeneration, providing a promising future in the clinical treatment of cartilage injury.

Comparison of Genetically Engineered Immunodeficient Animal Models for Nonclinical Testing of Stem Cell Therapies

For the recovery or replacement of dysfunctional cells and tissue—the goal of stem cell research—successful engraftment of transplanted cells and tissues are essential events. The event is largely dependent on the immune rejection of the recipient; therefore, the immunogenic evaluation of candidate cells or tissues in immunodeficient animals is important. Understanding the immunodeficient system can provide insights into the generation and use of immunodeficient animal models, presenting a unique system to explore the capabilities of the innate immune system. In this review, we summarize various immunodeficient animal model systems with different target genes as valuable tools for biomedical research. There have been numerous immunodeficient models developed by different gene defects, resulting in many different features in phenotype. More important, mice, rats, and other large animals exhibit very different immunological and physiological features in tissue and organs, including genetic background and a representation of human disease conditions. Therefore, the findings from this review may guide researchers to select the most appropriate immunodeficient strain, target gene, and animal species based on the research type, mutant gene effects, and similarity to human immunological features for stem cell research.

Allogeneic Umbilical Cord Blood-Derived Mesenchymal Stem Cell Implantation Versus Microfracture for Large, Full-Thickness Cartilage Defects in Older Patients: A Multicenter Randomized Clinical Trial and Extended 5-Year Clinical Follow-up

Background:

There is currently no optimal method for cartilage restoration in large, full-thickness cartilage defects in older patients.

Purpose:

To determine whether implantation of a composite of allogeneic umbilical cord blood–derived mesenchymal stem cells and 4% hyaluronate (UCB-MSC-HA) will result in reliable cartilage restoration in patients with large, full-thickness cartilage defects and whether any clinical improvements can be maintained up to 5 years postoperatively.

Study Design:

Randomized controlled trial; Level of evidence, 1.

Methods:

A randomized controlled phase 3 clinical trial was conducted for 48 weeks, and the participants then underwent extended 5-year observational follow-up. Enrolled were patients with large, full-thickness cartilage defects (International Cartilage Repair Society [ICRS] grade 4) in a single compartment of the knee joint, as confirmed by arthroscopy. The defect was treated either with UCB-MSC-HA implantation through mini-arthrotomy or with microfracture. The primary outcome was proportion of participants who improved by ≥1 grade on the ICRS Macroscopic Cartilage Repair Assessment (blinded evaluation) at 48-week arthroscopy. Secondary outcomes included histologic assessment; changes in pain visual analog scale (VAS) score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and International Knee Documentation Committee (IKDC) score from baseline; and adverse events.

Results:

Among 114 randomized participants (mean age, 55.9 years; 67% female; body mass index, 26.2 kg/m²), 89 completed the phase 3 clinical trial and 73 were enrolled in the 5-year follow-up study. The mean defect size was 4.9 cm² in the UCB-MSC-HA group and 4.0 cm² in the microfracture group (P = .051). At 48 weeks, improvement by ≥1 ICRS grade was seen in 97.7% of the UCB-MSC-HA group versus 71.7% of the microfracture group (P = .001); the overall histologic assessment score was also superior in the UCB-MSC-HA group (P = .036). Improvement in VAS pain, WOMAC, and IKDC scores were not significantly different between the groups at 48 weeks, however the clinical results were significantly better in the UCB-MSC-HA group at 3- to 5-year follow-up (P < .05). There were no differences between the groups in adverse events.

Conclusion:

In older patients with symptomatic, large, full-thickness cartilage defects with or without osteoarthritis, UCB-MSC-HA implantation resulted in improved cartilage grade at second-look arthroscopy and provided more improvement in pain and function up to 5 years compared with microfracture.

Registration:

NCT01041001, NCT01626677 (ClinicalTrials.gov identifier).

Accentuating the sources of mesenchymal stem cells as cellular therapy for osteoarthritis knees-a panoramic review

The large economic burden on the global health care systems is due to the increasing number of symptomatic osteoarthritis (OA) knee patients whereby accounting for greater morbidity and impaired functional quality of life. The recent developments and impulses in molecular and regenerative medicine have paved the way for inducing the biological active cells such as stem cells, bioactive materials, and growth factors towards the healing and tissue regenerative process. Mesenchymal stem cells (MSCs) act as a minimally invasive procedure that bridges the gap between pharmacological treatment and surgical treatment for OA. MSCs are the ideal cell-based therapy for treating disorders under a minimally invasive environment in conjunction with cartilage regeneration. Due to the worldwide recognized animal model for such cell-based therapies, global researchers have started using the various sources of MSCs towards cartilage regeneration. However, there is a lacuna in literature on the comparative efficacy and safety of various sources of MSCs in OA of the knee. Hence, the identification of a potential source for therapeutic use in this clinical scenario remains unclear. In this article, we compared the therapeutic effects of various sources of MSCs in terms of efficacy, safety, differentiation potential, durability, accessibility, allogenic preparation and culture expandability to decide the optimal source of MSCs for OA knee.

An Injectable Hydrogel Scaffold With Kartogenin-Encapsulated Nanoparticles for Porcine Cartilage Regeneration: A 12-Month Follow-up Study

BACKGROUND

Treatment of cartilage lesions is clinically challenging. A previous study demonstrated that a hyaluronic acid hydrogel (m-HA) with kartogenin (KGN)-loaded PLGA nanoparticles (m-HA+KGN treatment) achieved superior cartilage repair in a rabbit model. However, large animals serve as a bridge to translate animal outcomes into the clinic.

HYPOTHESES

(1) m-HA+KGN treatment could facilitate hyaline cartilage and subchondral bone tissue repair in a porcine model. (2) Defect size and type (full-thickness chondral vs osteochondral) influence the therapeutic efficacy of m-HA+KGN treatment.

STUDY DESIGN

Controlled laboratory study.

METHODS

48 minipigs were randomized into 3 treatment groups: m-HA hydrogel with KGN-loaded PLGA nanoparticles (m-HA+KGN treatment), m-HA hydrogel (m-HA treatment), and untreated (blank treatment). Full-thickness chondral (6.5 mm or 8.5 mm in diameter) or osteochondral (6.5 mm or 8.5 mm in diameter; 5-mm depth) defects were prepared in the medial femoral condyle. At 6 and 12 months postoperatively, defect repair was assessed by macroscopic appearance, magnetic resonance imaging (MRI), micro-computed tomography (µCT), and histologic and biomechanical tests.

RESULTS

The m-HA+KGN group exhibited superior gross and histological healing after evaluation at 6 and 12 months postoperatively. Improved quality of the repaired cartilage demonstrated by MRI and better subchondral bone reconstruction assessed by µCT were observed in the m-HA+KGN group. The m-HA+KGN group showed more hyaline-like cartilage exhibited by histological staining in terms of extracellular matrix, cartilage lacuna, and type II collagen. The biomechanical properties were improved in the m-HA+KGN group. With m-HA+KGN treatment, defects with a diameter of 6.5 mm or full-thickness chondral-type defects possessed significantly higher ICRS macroscopic and histological scores compared with diameter 8.5 mm or osteochondral-type defects.

CONCLUSION

(1) m-HA+KGN treatment facilitated hyaline cartilage and subchondral bone tissue repair in a porcine model at the 12-month follow-up. (2) m-HA+KGN treatment demonstrated better therapeutic efficacy in defects with a diameter of 6.5 mm or full-thickness chondral-type defects.

CLINICAL RELEVANCE

This study verified the efficacy of this innovative KGN release system on cartilage repair. The KGN release system can be injected into defect sites arthroscopically. This convenient and minimally invasive operation holds important prospects for clinical application.

Combined Transplantation of Mesenchymal Stem Cells and Endothelial Colony-Forming Cells Accelerates Refractory Diabetic Foot Ulcer Healing

Background

This study is aimed at investigating the effect of combined transplantation of umbilical cord mesenchymal stem cells (UCMSCs) and umbilical cord blood-derived endothelial colony-forming cells (ECFCs) on diabetic foot ulcer healing and at providing a novel therapy for chronic diabetic foot ulcer.

Methods

We reported the treatment of refractory diabetic foot ulcers in twelve patients. Among them, five patients had two or more wounds; thus, one wound in the same patient was treated with cell injection, and other wounds were regarded as self-controls. The remaining seven patients had only one wound; therefore, the difference between the area of wound before and after treatment was estimated. The UCMSCs and ECFCs were injected into the wound along with topically applied hyaluronic acid (HA).

Results

In this report, we compared the healing rate of multiple separate wounds in the same foot of the same patient: one treated with cell injection combined with topically applied HA-based hydrogel and was later covered by the hydrocolloid dressings, while the self-control wounds were only treated with conventional therapy and covered by the hydrocolloid dressings. The wound underwent cell injection showed accelerated healing in comparison to control wound within the first week after treatment. In other diabetic patients with only one refractory wound, the healing rate after cell transplantation was significantly faster than that before injection. Two large wounds healed without needing skin grafts after combination therapy of cell injection and HA. After four weeks of combination treatment, wound closure was reached in six patients, and the wounds of the other six patients were significantly reduced in size.

Conclusions

Our study suggests that the combination of UCMSCs, ECFCs, and HA can safely synergize the accelerated healing of refractory diabetic foot ulcers.

Advanced hydrogels for the repair of cartilage defects and regeneration

Cartilage defects are one of the most common symptoms of osteoarthritis (OA), a degenerative disease that affects millions of people world-wide and places a significant socio-economic burden on society. Hydrogels, which are a class of biomaterials that are elastic, and display smooth surfaces while exhibiting high water content, are promising candidates for cartilage regeneration. In recent years, various kinds of hydrogels have been developed and applied for the repair of cartilage defects in vitro or in vivo, some of which are hopeful to enter clinical trials. In this review, recent research findings and developments of hydrogels for cartilage defects repair are summarized. We discuss the principle of cartilage regeneration, and outline the requirements that have to be fulfilled for the deployment of hydrogels for medical applications. We also highlight the development of advanced hydrogels with tailored properties for different kinds of cartilage defects to meet the requirements of cartilage tissue engineering and precision medicine.

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The biotechnology of developing hydrogels for cartilage defects repair is promising.

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The principle for cartilage regeneration using hydrogels and requirements for clinical transformation are summarized.

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Advanced hydrogels with tailored properties for different kinds of cartilage defects are discussed.

Machine learning to predict mesenchymal stem cell efficacy for cartilage repair

Inconsistent therapeutic efficacy of mesenchymal stem cells (MSCs) in regenerative medicine has been documented in many clinical trials. Precise prediction on the therapeutic outcome of a MSC therapy based on the patient's conditions would provide valuable references for clinicians to decide the treatment strategies. In this article, we performed a meta-analysis on MSC therapies for cartilage repair using machine learning. A small database was generated from published in vivo and clinical studies. The unique features of our neural network model in handling missing data and calculating prediction uncertainty enabled precise prediction of post-treatment cartilage repair scores with coefficient of determination of 0.637 ± 0.005. From this model, we identified defect area percentage, defect depth percentage, implantation cell number, body weight, tissue source, and the type of cartilage damage as critical properties that significant impact cartilage repair. A dosage of 17 - 25 million MSCs was found to achieve optimal cartilage repair. Further, critical thresholds at 6% and 64% of cartilage damage in area, and 22% and 56% in depth were predicted to significantly compromise on the efficacy of MSC therapy. This study, for the first time, demonstrated machine learning of patient-specific cartilage repair post MSC therapy. This approach can be applied to identify and investigate more critical properties involved in MSC-induced cartilage repair, and adapted for other clinical indications.

Hyaluronic acid containing scaffolds ameliorate stem cell function for tissue repair and regeneration

Recent evidence based studies have proposed hyaluronic acid (HA) as an emerging biopolymer for various tissue engineering application. Meanwhile, stem cells (SCs) have also gained immense popularity for their tissue regenerative capacity. Thus, combining HA and stem cells for tissue engineering application have shown to foster tissue repair and regeneration process. HA possesses the ability to interact with SCs via cellular surface receptors along with the capacity to elicit the process of differentiation. The influence of HA on stem cells has been widely investigated in cartilage and bone repair but their properties of reducing inflammation has also been explored in various other tissue repair processes. In this review, we have provided an insight to the effect of crosslinked and non-crosslinked HA on various stem cells. Further, HA based scaffolds combined with stem cells have shown to have a synergistic effect in the regeneration capacity. Also, various chemically modified HA and biomolecules conjugated HA as a suitable carrier or matrix for stem cells delivery and the effect of HA in fine tuning the stem cells function is discussed.

Intra-articular Injection of Culture-Expanded Mesenchymal Stem Cells Without Adjuvant Surgery in Knee Osteoarthritis: A Systematic Review and Meta-analysis

BACKGROUND

Although many clinical studies have assessed the efficacy of mesenchymal stem cells (MSCs) in knee osteoarthritis, evidence on their efficacy remains unclear owing to heterogeneity of cell entity and concomitant procedures.

PURPOSE

To determine the efficacy of culture-expanded MSCs in knee osteoarthritis in terms of clinical outcome and cartilage repair via meta-analysis of randomized controlled trials (RCTs) without adjuvant surgery.

STUDY DESIGN

Meta-analysis.

METHODS

PubMed, Embase, the Cochrane Library, CINAHL, and Scopus were searched from inception to December 31, 2018. RCTs with culture-expanded MSCs for treating knee osteoarthritis were included. Studies with adjuvant surgery or cell concentrate were excluded. Quality was assessed by the Cochrane Collaboration risk-of-bias tool. For meta-analysis, data on clinical outcomes were measured using a visual analog scale (VAS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and data on cartilage repair were measured using the Whole-Organ Magnetic Resonance Imaging Score (WORMS); categorization related to improvement was extracted.

RESULTS

Six RCTs (203 patients) were included. Two studies were deemed to have a low risk of bias. In pooled analysis, the only significant difference was in the VAS score (mean difference, -13.55; 95% CI, -22.19 to -4.9). In cumulative pain analysis with VAS and WOMAC pain scores, there was significant improvement after treatment (standardized mean difference, -0.54; 95% CI, -0.85 to -0.23). There was no significant difference in cartilage repair assessed by magnetic resonance imaging (standardized mean difference, 0.11; 95% CI, -0.51 to 0.73), WORMS (standardized mean difference, 1.68; 95% CI -14.84 to 18.21), or categorical results (odds ratio, 1.56; 95% CI, 0.32-7.59).

CONCLUSION

Intra-articular injection of culture-expanded MSCs without adjuvant surgery can improve pain for patients experiencing knee osteoarthritis at short-term follow-up (6-12 months). However, evidence regarding function and cartilage repair remains limited.

Regeneration of hyaline cartilage in osteochondral lesion model using L-lysine magnetic nanoparticles labeled mesenchymal stem cells and their in vivo imaging

Treatment of osteochondral defects continues to pose a major challenge for patients and orthopedic surgeons due to the limited healing potential of articular cartilage. Mesenchymal stem cells (MSCs) possess therapeutic potential for the treatment of osteochondral pain and pathology. However, it is necessary to use proper labeling and imaging agent of stem cells that can decipher its role posttransplantation. A major limitation of routinely used contrast agents is signal dilution over a period of time which limits its use for further studies. At the same time, regeneration of fibrocartilage over native hyaline cartilage also limits the use of conventional therapies. The present study evaluates the efficacy of bone marrow-derived mesenchymal stem cells (BMSCs) for the treatment of osteochondral defect in rats with the regeneration of hyaline cartilage in situ and in vivo monitoring of the stem cells using L-lysine functionalized magnetic iron oxide nanoparticles (lys-IONPs). L-lysine stabilizes the iron oxide nanoparticles, enhances the biocompatibility, and provides functionalities for efficient stem cell labeling. in vitro toxic effects of lys-IONPs on mitochondrial impairment, morphological alterations, and actin cytoskeleton reveal minimum damage to BM-MSCs. Histological data (H and E, Masson's trichrome and immunohistochemistry) describe the early initiation of healing and regeneration of hyaline-like cartilage over fibrocartilage in stem cell treated groups. MR scans demonstrate generation of hypointense signals in lys-IONPs-BMSCs with improved signal intensity and minimum loss over 28 days revealing its use as a long-term stem cell labeling and imaging agent.

Exquisite design of injectable Hydrogels in Cartilage Repair

Cartilage damage is still a threat to human beings, yet there is currently no treatment available to fully restore the function of cartilage. Recently, due to their unique structures and properties, injectable hydrogels have been widely studied and have exhibited high potential for applications in therapeutic areas, especially in cartilage repair. In this review, we briefly introduce the properties of cartilage, some articular cartilage injuries, and now available treatment strategies. Afterwards, we propose the functional and fundamental requirements of injectable hydrogels in cartilage tissue engineering, as well as the main advantages of injectable hydrogels as a therapy for cartilage damage, including strong plasticity and excellent biocompatibility. Moreover, we comprehensively summarize the polymers, cells, and bioactive molecules regularly used in the fabrication of injectable hydrogels, with two kinds of gelation, i.e., physical and chemical crosslinking, which ensure the excellent design of injectable hydrogels for cartilage repair. We also include novel hybrid injectable hydrogels combined with nanoparticles. Finally, we conclude with the advances of this clinical application and the challenges of injectable hydrogels used in cartilage repair.

Nonoperative Applications of Placental Tissue Matrix in Orthopaedic Sports Injuries: A Review of Literature

OBJECTIVE

Recently, various amniotic tissue and placental-based tissue matrix (PTM) products have become increasingly available as a nonoperative treatment for tendinopathies and orthopaedic sports injuries. The aim of this review was to evaluate: (1) safety and efficacy of nonoperative use of PTM products, in acute and chronic tendon injuries and (2) the commercially available tissue options to better understand their differences.

DATA SOURCES

A comprehensive literature search was performed. Inclusion criteria were studies reporting on: (1) nonoperative uses of PTM therapy in sports injuries; and (2) clinical outcomes; in (3) human subjects. We excluded: (1) animal studies; (2) basic science studies; (3) non-English language literature; (4) review articles; and (5) duplicate studies. In addition, to determine the various product formulations, their tissue contents, and indications for use, we searched publicly available website content, marketing literature, and Food and Drug Administration (FDA) registration documents.

MAIN RESULTS

Current evidence investigated various PTM products for the treatment of various tendon injuries with demonstrated efficacy mainly in the short term with follow-up ranging between 6 weeks and 3 months. In addition, across all studies, no specific adverse events were reported. Substantial differences exist among the currently available products due to variations in their tissue source, formulations, processing methods, method of sterilization, preservation, and storage, indications for use, and FDA regulation.

CONCLUSIONS

Placental- and amniotic membrane-derived tissues seem to be safe for the nonoperative treatment of tendinopathies. However, several factors may affect the efficacy and safety profile of these products, and the orthopaedic surgeons should be aware of the differences.

High tibial osteotomy with human umbilical cord blood-derived mesenchymal stem cells implantation for knee cartilage regeneration

BACKGROUND

High tibial osteotomy (HTO) is a well-established method for the treatment of medial compartment osteoarthritis of the knee with varus deformity. However, HTO alone cannot adequately repair the arthritic joint, necessitating cartilage regeneration therapy. Cartilage regeneration procedures with concomitant HTO are used to improve the clinical outcome in patients with varus deformity.

AIM

To evaluate cartilage regeneration after implantation of allogenic human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) with concomitant HTO.

METHODS

Data for patients who underwent implantation of hUCB-MSCs with concomitant HTO were evaluated. The patients included in this study were over 40 years old, had a varus deformity of more than 5°, and a full-thickness International Cartilage Repair Society (ICRS) grade IV articular cartilage lesion of more than 4 cm² in the medial compartment of the knee. All patients underwent second-look arthroscopy during hardware removal. Cartilage regeneration was evaluated macroscopically using the ICRS grading system in second-look arthroscopy. We also assessed the effects of patient characteristics, such as trochlear lesions, age, and lesion size, using patient medical records.

RESULTS

A total of 125 patients were included in the study, with an average age of 58.3 ± 6.8 years (range: 43-74 years old); 95 (76%) were female and 30 (24%) were male. The average hip-knee-ankle (HKA) angle for measuring varus deformity was 7.6° ± 2.4° (range: 5.0-14.2°). In second-look arthroscopy, the status of medial femoral condyle (MFC) cartilage was as follows: 73 (58.4%) patients with ICRS grade I, 37 (29.6%) with ICRS grade II, and 15 (12%) with ICRS grade III. No patients were staged with ICRS grade IV. Additionally, the scores [except International Knee Documentation Committee (IKDC) at 1 year] of the ICRS grade I group improved more significantly than those of the ICRS grade II and III groups.

CONCLUSION

Implantation of hUCB-MSCs with concomitant HTO is an effective treatment for patients with medial compartment osteoarthritis and varus deformity. Regeneration of cartilage improves the clinical outcomes for the patients.

Current perspectives in stem cell therapies for osteoarthritis of the knee

Mesenchymal stem cells (MSCs) are emerging as an attractive option for osteoarthritis (OA) of the knee joint, due to their marked disease-modifying ability and chondrogenic potential. MSCs can be isolated from various organ tissues, such as bone marrow, adipose tissue, synovium, umbilical cord blood, and articular cartilage with similar phenotypic characteristics but different proliferation and differentiation potentials. They can be differentiated into a variety of connective tissues such as bone, adipose tissue, cartilage, intervertebral discs, ligaments, and muscles. Although several studies have reported on the clinical efficacy of MSCs in knee OA, the results lack consistency. Furthermore, there is no consensus regarding the proper cell dosage and application method to achieve the optimal effect of stem cells. Therefore, the purpose of this study is to review the characteristics of various type of stem cells in knee OA, especially MSCs. Moreover, we summarize the clinical issues faced during the application of MSCs.

Human umbilical cord blood-derived mesenchymal stem cell implantation for osteoarthritis of the knee

INTRODUCTION

This study aimed to investigate the clinical outcomes after human umbilical cord blood-derived mesenchymal stem cell (hUCB-MSC) implantation for medial compartment (MC) osteoarthritis of the knee.

MATERIALS AND METHODS

Inclusion criteria were patients older than 60 years, with a kissing lesion of the MC, a full-thickness chondral defect ≥ 4 cm² of the medial femoral condyle (MFC), and a varus deformity ≥ 3° on a long cassette scanogram. The mean age was 64.9 ± 4.4 years and the mean chondral defect of the MFC was 7.2 ± 1.9 cm². A mixture of sodium hyaluronate and hUCB-MSC was implanted into the chondral defect and a high tibial osteotomy was performed in all patients. International Knee Documentation Committee (IKDC), visual analog scale (VAS), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were evaluated preoperatively and 1 year and 2 years postoperatively. Cartilage regeneration was evaluated in 14 (56%) patients by second-look arthroscopy at 1 year postoperatively.

RESULTS

Twenty-five patients underwent hUBC-MSC implantation. IKDC, VAS, and WOMAC scores at 1 year and 2 years improved significantly compared to preoperative scores. These scores at 1 year and 2 years were not significantly different between the body mass index (BMI) < 25 group and BMI ≥ 25 group. However, the < 65-year-old group showed superior IKDC scores at 1 year and 2 years and VAS score at 2 years than the ≥ 65-year-old group. Younger age and larger size of the chondral defect were associated with a significantly greater improvement in IKDC, VAS and WOMAC scores at 2 years. Second-look arthroscopy demonstrated International Cartilage Repair Society-Cartilage Repair Assessment grade I in six (42.9%) patients and grade II in eight (57.1%).

CONCLUSIONS

hUCB-MSC implantation regenerated cartilage satisfactorily and showed satisfactory clinical outcomes in patients older than 60 years who had MC osteoarthritis.

Cocktail of Hyaluronic Acid and Human Amniotic Mesenchymal Cells Effectively Repairs Cartilage Injuries in Sodium Iodoacetate-Induced Osteoarthritis Rats

Osteoarthritis (OA) is one of the most common refractory degenerative articular cartilage diseases. Human amniotic mesenchymal cells (hAMSCs) have emerged as a promising stem cell source for cartilage repair, and hyaluronic acid (HA) has proven to be a versatile regulator for stem cell transplantation. Herein, an effective and straightforward intra-articular injection therapy using a cocktail of hAMSCs and HA was developed to treat knee OA in a rat model. The injured cartilage was remarkably regenerated, yielding results comparable to normal cartilage levels after 56 days of treatment. Both hAMSCs and HA were indispensable organic components in this therapy, in which HA could synergistically enhance the effects of hAMSCs on cartilage repair. The regenerative mechanism was attributed to the fact that the addition of HA comprehensively enhances the activities of hAMSCs, including chondrogenic differentiation, proliferation, colonization, and regenerative modulation. This cocktail paves a new avenue for injection therapy to treat OA, holding the potential to realize rapid clinical translation.

Evaluation of biomimetic hyaluronic-based hydrogels with enhanced endogenous cell recruitment and cartilage matrix formation

Biomaterials play a pivotal role in cell-free cartilage repair approaches, where cells must migrate through the scaffold, fill the defect, and then proliferate and differentiate facilitating tissue remodeling. Here we used multiple assays to test the influence of chemokines and growth factors on cell migration and cartilage repair in two different hyaluronan (HA)-based hydrogels. We first investigated bone marrow Mesenchymal Stromal Cells (BMSC) migration in vitro, in response to different concentrations of platelet-derived growth factor-BB (PDGF-BB), chemokine ligand 5 (CCL5/RANTES) and stromal cell-derived factor 1 (SDF-1), using a 3D spheroid-based assay. PDGF-BB was selected as most favourable chemotactic agent, and MSC migration was assessed in the context of physical impediment to cell recruitment by testing Fibrin-HA and HA-Tyramine hydrogels of different cross-linking densities. Supplementation of PDGF-BB stimulated progressive migration of MSC through the gels over time. We then investigated in situ cell migration into the hydrogels with and without PDGF-BB, using a cartilage-bone explant model implanted subcutaneously in athymic mice. In vivo studies show that when placed into an osteochondral defect, both hydrogels supported endogenous cell infiltration and provided an amenable microenvironment for cartilage production. These processes were best supported in Fibrin-HA hydrogel in the absence of PDGF-BB. This study used an advanced preclinical testing platform to select an appropriate microenvironment provided by implanted hydrogels, demonstrating that HA-based hydrogels can promote the initial and critical step of endogenous cell recruitment and circumvent some of the clinical challenges in cartilage tissue repair. STATEMENT OF SIGNIFICANCE: The challenge of articular cartilage repair arises from its complex structure and architecture, which confers the unique mechanical behavior of the extracellular matrix. The aim of our research is to identify biomaterials for implants that can support migration of endogenous stem and progenitor cell populations from cartilage and bone tissue, in order to permanently replace damaged cartilage with the original hyaline structure. Here, we present an in vitro 3D spheroid-based migration assay and an osteochondral defect model, which provide the opportunity to assess biomaterials and biomolecules, and to get stronger experimental evidence of the not well-characterized dynamic process of endogenous cells colonization in an osteochondral defect. Furthermore, the delicate step of early cell migration into biomaterials towards functional tissue engineering is reproduced. These tests can be used for pre-clinical testing of newly developed material designs in the field of scaffold engineering.

Allogenic umbilical cord blood-derived mesenchymal stem cells implantation for the treatment of juvenile osteochondritis dissecans of the knee

BACKGROUND

Osteochondritis dissecans (OCD) is a pathologic condition accompanied by the gradual destruction of subchondral bone and defects in the overlying articular cartilage.This case series reports the results of allogenic human umbilical cord blood-derived mesenchymal stem cell (hUCB-MSC) implantation for the treatment of osteochondral defect in two cases of juvenile osteochondritis dissecans.

CASE PRESENTATION

Two patients with osteochondral defect of the knee recovered from the disease enough to begin major exercise 1 year after hUCB-MSCs implantation. The IKDC, VAS, and Tegner score of the two patients showed an excellent improvement and concurrent arthroscopy was performed; cartilage regeneration of ICRS grade 1 similar to normal was observed. The modified two-dimensional MOCART scores increased in both cases over time.

CONCLUSION

This is the first case series detailing the results of treating juvenile OCD lesions using hUCB-MSCs. This could be an option for treating juvenile OCD.

Anatomical feature of knee joint in Aachen minipig as a novel miniature pig line for experimental research in orthopaedics

BACKGROUND

The pig is a commonly used large animal model, since pigs share anatomical and physiological similarities with humans. In contrast to other experimental pig lines the Aachen minipig, as a robust novel minipig does not require housing with any barrier. To estimate transferability of results to human conditions, pig lines should be thoroughly characterized.

PURPOSE

Therefore, we analyzed the anatomical pecularities of the knee joint of the novel "Aachen minipig" line raised for experimental conditions.

METHODS

Eight knee joints of four adult Aachen minipigs were dissected measuring the dimensions of typical landmarks using a digital caliper. Hybrid pig and human knee joints served as controls. Cartilage of the Aachen minipig (trochlear groove, femoral condyles, menisci) were assessed histologically.

RESULTS

The Aachen minipig shared its knee joint anatomy with the hybrid pig. In comparison to humans, peculiarities of the pig were demonstrated in the Aachen minipig: the lateral meniscus and the lateral tibial joint surface were significantly longer than the medial counterparts. The fibular head was covered by fibrocartilage and completely integrated into the lateral lower joint surface. The cartilage at the joint areas usually used for cartilage repair studies was in average 0.66±0.04mm thick. The porcine anterior cruciate ligament (ACL) attached with two bundles at the anterior tibial plateau separated from each other by the lateral anterior meniscotibial ligament. Aachen minipig articular and meniscal cartilage presented the typical histoarchitecture.

CONCLUSIONS

The Aachen minipig reflects porcine anatomical peculiarities, which should be considered, especially for meniscus and ACL reconstruction.

Dynamic and Cell-Infiltratable Hydrogels as Injectable Carrier of Therapeutic Cells and Drugs for Treating Challenging Bone Defects

Biopolymeric hydrogels have been widely used as carriers of therapeutic cells and drugs for biomedical applications. However, most conventional hydrogels cannot be injected after gelation and do not support the infiltration of cells because of the static nature of their network structure. Here, we develop unique cell-infiltratable and injectable (Ci-I) gelatin hydrogels, which are physically cross-linked by weak and highly dynamic host-guest complexations and are further reinforced by limited chemical cross-linking for enhanced stability, and then demonstrate the outstanding properties of these Ci-I gelatin hydrogels. The highly dynamic network of Ci-I hydrogels allows injection of prefabricated hydrogels with encapsulated cells and drugs, thereby simplifying administration during surgery. Furthermore, the reversible nature of the weak host-guest cross-links enables infiltration and migration of external cells into Ci-I gelatin hydrogels, thereby promoting the participation of endogenous cells in the healing process. Our findings show that Ci-I hydrogels can mediate sustained delivery of small hydrophobic molecular drugs (e.g., icaritin) to boost differentiation of stem cells while avoiding the adverse effects (e.g., in treatment of bone necrosis) associated with high drug dosage. The injection of Ci-I hydrogels encapsulating mesenchymal stem cells (MSCs) and drug (icaritin) efficiently prevented the decrease in bone mineral density (BMD) and promoted in situ bone regeneration in an animal model of steroid-associated osteonecrosis (SAON) of the hip by creating the microenvironment favoring the osteogenic differentiation of MSCs, including the recruited endogenous cells. We believe that this is the first demonstration on applying injectable hydrogels as effective carriers of therapeutic cargo for treating dysfunctions in deep and enclosed anatomical sites via a minimally invasive procedure.

Comparison of Undifferentiated Versus Chondrogenic Predifferentiated Mesenchymal Stem Cells Derived From Human Umbilical Cord Blood for Cartilage Repair in a Rat Model

BACKGROUND

Human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) have gained much interest as a promising cell source for regenerative medicine owing to the noninvasive collection, availability, high expansion capacity, and low immunogenicity. However, few in vivo studies have reported the use of hUCB-MSCs on cartilage repair. Moreover, little study has been conducted on the effects of chondrogenic predifferentiation of hUCB-MSCs on cartilage repair.

PURPOSE

To compare the effectiveness of transplanting undifferentiated versus chondrogenic predifferentiated mesenchymal stem cells (MSCs) for treating osteochondral defects.

STUDY DESIGN

Controlled laboratory study.

METHODS

Critical-sized osteochondral defects were created in the trochlear grooves of rat femurs. In 20 rats, a composite of chondrogenic predifferentiated hUCB-MSCs (chondro-MSCs) and 4% hyaluronic acid (HA) hydrogel was transplanted into defects in the right knees, whereas undifferentiated hUCB-MSCs (undiff-MSCs) and 4% HA hydrogel were transplanted into the left knees. In the control groups, 4% HA hydrogel without MSCs was transplanted into defects in the right knees, and the defects in the left knees were left untreated in 20 rats. The cartilage repair was evaluated at 8 and 16 weeks after surgery.

RESULTS

Transplanting undiff-MSCs resulted in overall superior cartilage repair as compared with chondro-MSCs, HA alone, or no treatment. The articular surfaces of the defect sites in the undiff-MSC group were relatively smoother than those of the other treatments. The undiff-MSC group showed cellular morphology and arrangement similar to surrounding normal articular cartilage tissue at 16 weeks, both of which were also better than those of the other groups. In addition, the undiff-MSC group showed coloration similar to surrounding normal articular cartilage tissue at 16 weeks in safranin O and type II collagen immunohistochemical staining. The histological scores also revealed that cartilage repair with undiff-MSCs was better than that with chondro-MSCs, HA alone, or no treatment ( P < .05 in all).

CONCLUSION

This study demonstrated that treatment with undiff-MSCs resulted in more favorable cartilage repair than that with chondro-MSCs in a rat model. These findings indicate that chondrogenic predifferentiation of MSCs before transplantation does not enhance cartilage repair.

CLINICAL RELEVANCE

The results of this study support the use of undifferentiated MSCs, rather than chondrogenic predifferentiated MSCs, as a stem cell therapy strategy for cartilage repair.

Intra-articular Mesenchymal Stem Cells in Osteoarthritis of the Knee: A Systematic Review of Clinical Outcomes and Evidence of Cartilage Repair

PURPOSE

To provide a systematic review of the clinical literature reporting the efficacy of mesenchymal stem cells (MSCs) in terms of clinical outcomes including pain and function and cartilage repair in patients with osteoarthritis.

METHODS

We systematically reviewed any studies investigating clinical outcomes and cartilage repair after the clinical application of cell populations containing MSCs in human subjects with knee osteoarthritis through MEDLINE, EMBASE, the Cochrane Library, CINAHL, Web of Science, and Scopus. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. Studies with a level of evidence of IV or V were excluded. Methodological quality was assessed using the Modified Coleman Methodology Score. Clinical outcomes were assessed using clinical scores, and cartilage repair was assessed using magnetic resonance imaging and second-look arthroscopy findings.

RESULTS

A total of 17 studies that met the criteria of 50 full-text studies were included in this review, with 6 randomized controlled trials, 8 prospective observational studies, and 3 retrospective case-control studies. Among 17 studies, 8 studies used bone marrow-derived MSCs, 6 used adipose tissue-derived stromal vascular fraction, 2 used adipose tissue-derived MSCs, and 1 used umbilical cord blood-derived MSCs. All studies except 2 reported significantly better clinical outcomes in the MSC group or improved clinical outcomes at final follow-up. In terms of cartilage repair, 9 of 11 studies reported improvement of the cartilage state on magnetic resonance imaging, and 6 of 7 studies reported repaired tissue on second-look arthroscopy. The mean Modified Coleman Methodology Score was 55.5 ± 15.5 (range, 28-74).

CONCLUSIONS

Intra-articular MSCs provide improvements in pain and function in knee osteoarthritis at short-term follow-up (<28 months) in many cases. Some efficacy has been shown of MSCs for cartilage repair in osteoarthritis; however, the evidence of efficacy of intra-articular MSCs on both clinical outcomes and cartilage repair remains limited.

LEVEL OF EVIDENCE

Level III; systematic review of level I, II, and III studies.

Transplanting human umbilical cord mesenchymal stem cells and hyaluronate hydrogel repairs cartilage of osteoarthritis in the minipig model

Objectives:

Osteoarthritis (OA) is a chronic disease of degenerative joints. Mesenchymal stem cells (MSCs) have been used for cartilage regeneration in OA. We investigated the therapeutic potential of human umbilical cord-derived MSCs (HUCMSCs) with hyaluronic acid (HA) hydrogel transplanted into a porcine OA preclinical model.

Materials and Methods:

The HUCMSCs were characterized with respect to morphology, surface markers, and differentiation capabilities. Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) was used to examine gene expressions in a HUCMSC–HA coculture. Two healthy female minipigs weighing 30–40 kg and aged approximately 4 months were used in this large animal study. A full-thickness chondral injury was created in the trochlear groove of each of the pig's rear knees. After 3 weeks, a second osteochondral defect was created. Then, 1.5 mL of a HUCMSC (5 × 10⁶ cells) and HA composite (4%) was transplanted into the chondral-injured area in the right knee of each pig. Using the same surgical process, an osteochondral defect (untreated) was created in the left knee as a control. The pigs were sacrificed 12 weeks after transplantation. Macroscopic and microscopic histologies, qRT-PCR, and immunostaining evaluated the degree of chondral degradation.

Results:

The HUCMSCs exhibited typical MSC characteristics, including spindle morphology, expression of surface markers (positive for CD29, CD4, CD73, CD90, and human leukocyte antigen [HLA]-ABC; negative for CD34, CD45, and HLA-DR), and multipotent differentiation (adipogenesis, osteogenesis, and chondrogenesis). More extensive proliferation of HUCMSCs was noted with 4% and 25% of HA than without HA. Expression of COL2A1 and aggrecan in the HUCMSC-derived chondrocytes was increased when HA was included. The treated knees showed significant gross and histological improvements in hyaline cartilage regeneration when compared to the control knees. The International Cartilage Repair Society histological score was higher for the treated knees than the control knees.

Conclusion:

Our findings suggest that cartilage regeneration using a mixture of HUCMSCs and HA in a large animal model may be an effective treatment for OA, and this study is a stepping stone toward the future clinical trials.

Intra-articular Mesenchymal Stem Cell Therapy for the Human Joint: A Systematic Review

BACKGROUND

Stem cell therapy is emerging as a potential treatment of osteoarthritis (OA) and chondral defects (CDs). However, there is a great deal of heterogeneity in the literature. The indications for stem cell use, the ideal tissue source, and the preferred outcome measures for stem cell-based treatments have yet to be determined.

PURPOSE

To provide clinicians with a comprehensive overview of the entire body of the current human literature investigating the safety and efficacy of intra-articular mesenchymal stem cell (MSC) therapy in all joints.

METHODS

To provide a comprehensive overview of the current literature, all clinical studies investigating the safety and efficacy of intra-articular MSC therapy were included. PubMed, MEDLINE, and Cochrane Library databases were searched for published human clinical trials involving the use of MSCs for the treatment of OA and CDs in all joints. A total of 3867 publications were screened.

RESULTS

Twenty-eight studies met the criteria to be included in this review. Fourteen studies treating osteoarthritis and 14 studies treating focal chondral defects were included. MSCs originating from bone marrow (13), adipose tissue (12), synovial tissue (2), or peripheral blood (2) were administered to 584 distinct individuals. MSCs were administered into the knee (523 knees), foot/ankle (61), and hip (5). The mean follow-up time was 24.4 months after MSC therapy. All studies reported improvement from baseline in at least 1 clinical outcome measure, and no study reported major adverse events attributable to MSC therapy.

DISCUSSION

The studies included in this review suggest that intra-articular MSC therapy is safe. While clinical and, in some cases, radiological improvements were reported for both OA and CD trials, the overall quality of the literature was poor, and heterogeneity and lack of reproducibility limit firm conclusions regarding the efficacy of these treatments.

CONCLUSION

This review provides strong evidence that autologous intra-articular MSC therapy is safe, with generally positive clinical outcomes.

Application of Cord Blood and Cord Blood-Derived Induced Pluripotent Stem Cells for Cartilage Regeneration

Regeneration of articular cartilage is of great interest in cartilage tissue engineering since articular cartilage has a low regenerative capacity. Due to the difficulty in obtaining healthy cartilage for transplantation, there is a need to develop an alternative and effective regeneration therapy to treat degenerative or damaged joint diseases. Stem cells including various adult stem cells and pluripotent stem cells are now actively used in tissue engineering. Here, we provide an overview of the current status of cord blood cells and induced pluripotent stem cells derived from these cells in cartilage regeneration. The abilities of these cells to undergo chondrogenic differentiation are also described. Finally, the technical challenges of articular cartilage regeneration and future directions are discussed.

Comparative efficacy of stem cells and secretome in articular cartilage regeneration: a systematic review and meta-analysis

Articular cartilage defect remains the most challenging joint disease due to limited intrinsic healing capacity of the cartilage that most often progresses to osteoarthritis. In recent years, stem cell therapy has evolved as therapeutic strategies for articular cartilage regeneration. However, a number of studies have shown that therapeutic efficacy of stem cell transplantation is attributed to multiple secreted factors that modulate the surrounding milieu to evoke reparative processes. This systematic review and meta-analysis aim to evaluate and compare the therapeutic efficacy of stem cell and secretome in articular cartilage regeneration in animal models. We systematically searched the PubMed, CINAHL, Cochrane Library, Ovid Medline and Scopus databases until August 2017 using search terms related to stem cells, cartilage regeneration and animals. A random effect meta-analysis of the included studies was performed to assess the treatment effects on new cartilage formation on an absolute score of 0-100% scale. Subgroup analyses were also performed by sorting studies independently based on similar characteristics. The pooled analysis of 59 studies that utilized stem cells significantly improved new cartilage formation by 25.99% as compared with control. Similarly, the secretome also significantly increased cartilage regeneration by 26.08% in comparison to the control. Subgroup analyses revealed no significant difference in the effect of stem cells in new cartilage formation. However, there was a significant decline in the effect of stem cells in articular cartilage regeneration during long-term follow-up, suggesting that the duration of follow-up is a predictor of new cartilage formation. Secretome has shown a similar effect to stem cells in new cartilage formation. The risk of bias assessment showed poor reporting for most studies thereby limiting the actual risk of bias assessment. The present study suggests that both stem cells and secretome interventions improve cartilage regeneration in animal trials. Graphical abstract ᅟ.

Stem Cell Therapy for Articular Cartilage Repair: Review of the Entity of Cell Populations Used and the Result of the Clinical Application of Each Entity

BACKGROUND

Following successful preclinical studies, stem cell therapy is emerging as a candidate for the treatment of articular cartilage lesions. Because stem cell therapy for cartilage repair in humans is at an early phase, confusion and errors are found in the literature regarding use of the term stem cell therapy in this field.

PURPOSE

To provide an overview of the outcomes of cartilage repair, elucidating the various cell populations used, and thus reduce confusion with regard to using the term stem cell therapy.

STUDY DESIGN

Systematic review.

METHODS

The authors systematically reviewed any studies on clinical application of mesenchymal stem cells (MSCs) in human subjects. A comprehensive search was performed in MEDLINE, EMBASE, the Cochrane Library, CINAHL, Web of Science, and Scopus for human studies that evaluated articular cartilage repair with cell populations containing MSCs. These studies were classified as using bone marrow-derived MSCs, adipose tissue-derived MSCs, peripheral blood-derived MSCs, synovium-derived MSCs, and umbilical cord blood-derived MSCs according to the entity of cell population used.

RESULTS

Forty-six clinical studies were identified to focus on cartilage repair with MSCs: 20 studies with bone marrow-derived MSCs, 21 studies with adipose tissue-derived MSCs, 3 studies with peripheral blood-derived MSCs, 1 study with synovium-derived MSCs, and 1 study with umbilical cord blood-derived MSCs. All clinical studies reported that cartilage treated with MSCs showed favorable clinical outcomes in terms of clinical scores or cartilage repair evaluated by MRI. However, most studies were limited to case reports and case series. Among these 46 clinical studies, 18 studies erroneously referred to adipose tissue-derived stromal vascular fractions as "adipose-derived MSCs," 2 studies referred to peripheral blood-derived progenitor cells as "peripheral blood-derived MSCs," and 1 study referred to bone marrow aspirate concentrate as "bone marrow-derived MSCs."

CONCLUSION

Limited evidence is available regarding clinical benefit of stem cell therapy for articular cartilage repair. Because the literature contains substantial errors in describing the therapeutic cells used, researchers need to be alert and observant of proper terms, especially regarding whether the cells used were stem cells or cell populations containing a small portion of stem cells, to prevent confusion in understanding the results of a given stem cell-based therapy.

Advances in stem cell therapy for cartilage regeneration in osteoarthritis

INTRODUCTION

Osteoarthritis (OA) is a progressive joint disease that compromises the structural integrity of cartilage tissue. Conventional treatments based on medication or surgery are nowadays inefficient and cell-based therapy has emerged as one of the most promising methods for cartilage regeneration. The first therapy developed for cartilage defects was autologous chondrocyte implantation, but in the last few decades stem cells (SCs) from different sources have been proposed as a possible alternative for OA.

AREAS COVERED

SC sources and available delivery procedures (scaffolds/hydrogels) are presented, along with the main issues arisen in this regard. Thereafter, preclinical and clinical trials performed in recent years are reviewed in order to take a glance toward the potential benefits that such therapies could deliver to the patients.

EXPERT OPINION

SCs have proven their potential and safety for OA treatment. Nevertheless, there are still many questions to be resolved before their widespread used in clinical practice, such as the treatment mechanism, the best cell source, the most appropriate processing method, the most effective dose and delivery procedure, and their efficacy. In this sense, long-term follow-up and larger randomized controlled trials utilizing standardized and established outcome scores are mandatory to make objective conclusions.

Stem Cells for Cartilage Repair: Preclinical Studies and Insights in Translational Animal Models and Outcome Measures

Due to the restricted intrinsic capacity of resident chondrocytes to regenerate the lost cartilage postinjury, stem cell-based therapies have been proposed as a novel therapeutic approach for cartilage repair. Moreover, stem cell-based therapies using mesenchymal stem cells (MSCs) or induced pluripotent stem cells (iPSCs) have been used successfully in preclinical and clinical settings. Despite these promising reports, the exact mechanisms underlying stem cell-mediated cartilage repair remain uncertain. Stem cells can contribute to cartilage repair via chondrogenic differentiation, via immunomodulation, or by the production of paracrine factors and extracellular vesicles. But before novel cell-based therapies for cartilage repair can be introduced into the clinic, rigorous testing in preclinical animal models is required. Preclinical models used in regenerative cartilage studies include murine, lapine, caprine, ovine, porcine, canine, and equine models, each associated with its specific advantages and limitations. This review presents a summary of recent in vitro data and from in vivo preclinical studies justifying the use of MSCs and iPSCs in cartilage tissue engineering. Moreover, the advantages and disadvantages of utilizing small and large animals will be discussed, while also describing suitable outcome measures for evaluating cartilage repair.

The Placenta: Applications in Orthopaedic Sports Medicine

BACKGROUND

Placenta has a long history of use for treating burns and wounds. It is a rich source of collagen and other extracellular matrix proteins, tissue reparative growth factors, and stem cells, including mesenchymal stem cells (MSCs). Recent data show its therapeutic potential for orthopaedic sports medicine indications.

PURPOSE

To provide orthopaedic surgeons with an anatomic description of the placenta, to characterize its cellular composition, and to review the literature reporting the use of placenta-derived cells and placental tissue allografts for orthopaedic sports medicine indications in animal models and in humans.

STUDY DESIGN

Systematic review.

METHODS

Using a total of 63 keyword combinations, the PubMed and MEDLINE databases were searched for published articles describing the use of placental cells and/or tissue for orthopaedic sports medicine indications. Information was collected on placental tissue type, indications, animal model, study design, treatment regimen, safety, and efficacy outcomes. Results were categorized by indication and subcategorized by animal model.

RESULTS

Outcomes for 29 animal studies and 6 human studies reporting the use of placenta-derived therapeutics were generally positive; however, the placental tissue source, clinical indication, and administration route were highly variable across these studies. Fourteen animal studies described the use of placental tissue for tendon injuries, 13 studies for osteoarthritis or articular cartilage injuries, 3 for ligament injuries, and 1 for synovitis. Both placenta-derived culture-expanded cells (epithelial cells or MSCs) and placental tissue allografts were used in animal studies. In all human studies, commercial placental allografts were used. Five of 6 human studies examined the treatment of foot and ankle pathological conditions, and 1 studied the treatment of knee osteoarthritis.

CONCLUSION

A review of the small number of reported studies revealed a high degree of variability in placental cell types, placental tissue preparation, routes of administration, and treatment regimens, which prohibits making any definitive conclusions. Currently, the clinical use of placenta is limited to only commercial placental tissue allografts, as there are no placenta-derived biological drugs approved for the treatment of orthopaedic sports medicine conditions in the United States. However, this review shows that the application of placental cells or tissue allografts appears to be safe and has potential to improve outcomes for orthopaedic sports medicine indications.

Current and novel injectable hydrogels to treat focal chondral lesions: Properties and applicability

Focal chondral lesions and early osteoarthritis (OA) are responsible for progressive joint pain and disability in millions of people worldwide, yet there is currently no surgical joint preservation treatment available to fully restore the long term functionality of cartilage. Limitations of current treatments for cartilage defects have prompted the field of cartilage tissue engineering, which seeks to integrate engineering and biological principles to promote the growth of new cartilage to replace damaged tissue. Toward improving cartilage repair, hydrogel design has advanced in recent years to improve their utility. Injectable hydrogels have emerged as a promising scaffold due to their wide range of properties, the ability to encapsulate cells within the material, and their ability to provide cues for cell differentiation. Some of these advances include the development of improved control over in situ gelation (e.g., light), new techniques to process hydrogels (e.g., multi-layers), and better incorporation of biological signals (e.g., immobilization, controlled release, and tethering). This review summarises the innovative approaches to engineer injectable hydrogels toward cartilage repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:64-75, 2018.

Large Animal Models for Osteochondral Regeneration

Namely, in the last two decades, large animal models - small ruminants (sheep and goats), pigs, dogs and horses - have been used to study the physiopathology and to develop new therapeutic procedures to treat human clinical osteoarthritis. For that purpose, cartilage and/or osteochondral defects are generally performed in the stifle joint of selected large animal models at the condylar and trochlear femoral areas where spontaneous regeneration should be excluded. Experimental animal care and protection legislation and guideline documents of the US Food and Drug Administration, the American Society for Testing and Materials and the International Cartilage Repair Society should be followed, and also the specificities of the animal species used for these studies must be taken into account, such as the cartilage thickness of the selected defect localization, the defined cartilage critical size defect and the joint anatomy in view of the post-operative techniques to be performed to evaluate the chondral/osteochondral repair. In particular, in the articular cartilage regeneration and repair studies with animal models, the subchondral bone plate should always be taken into consideration. Pilot studies for chondral and osteochondral bone tissue engineering could apply short observational periods for evaluation of the cartilage regeneration up to 12 weeks post-operatively, but generally a 6- to 12-month follow-up period is used for these types of studies.

The Application of Stem Cells from Different Tissues to Cartilage Repair

The degeneration of articular cartilage represents an ongoing challenge at the clinical and basic level. Tissue engineering and regenerative medicine using stem/progenitor cells have emerged as valid alternatives to classical reparative techniques. This review offers a brief introduction and overview of the field, highlighting a number of tissue sources for stem/progenitor cell populations. Emphasis is given to recent developments in both clinical and basic sciences. The relative strengths and weaknesses of each tissue type are discussed.