Acemannan increased bone surface, bone volume, and bone density in a calvarial defect model in skeletally-mature rats

Acemannan coated, cobalt-doped biphasic calcium phosphate nanoparticles for immunomodulation regulated bone regeneration

Biomaterials are used as scaffolds in bone regeneration to facilitate the restoration of bone tissues. The local immune microenvironment affects bone repair but the role of immune response in biomaterial-facilitated osteogenesis has been largely overlooked and it presents a major knowledge gap in the field. Nanomaterials that can modulate M1 to M2 macrophage polarization and, thus, promote bone repair are known. This study investigates a novel approach to accelerate bone healing by using acemannan coated, cobalt-doped biphasic calcium phosphate nanoparticles to promote osteogenesis and modulate macrophage polarization to provide a prohealing microenvironment for bone regeneration. Different concentrations of cobalt were doped in biphasic calcium phosphate nanoparticles, which were further coated with acemannan polymer and characterized. The nanoparticles showed >90% cell viability and enhanced cell proliferation along with osteogenic differentiation as demonstrated by the enhanced alkaline phosphatase activity and osteogenic calcium deposition. The morphology of MC3T3-E1 cells remained unchanged even after treatment with nanoparticles. Acemannan coated nanoparticles were also able to decrease the expression of M1 markers, iNOS, and CD68 and enhance the expression of M2 markers, CD206, CD163, and Arg-1 as indicated by RT-qPCR, flow cytometry, and ICC studies. The findings show that acemannan coated nanoparticles can create a supportive immune milieu by inducing and promoting the release of osteogenic markers, and by causing a reduction in inflammatory markers, thus helping in efficient bone regeneration. As per our knowledge, this is the first study showing the combined effect of acemannan and cobalt for bone regeneration using immunomodulation. The work presents a novel approach for enhancing osteogenesis and macrophage polarization, thus, offering a potent strategy for effective bone regeneration.

Synthetic Calcium-Phosphate Materials for Bone Grafting

Synthetic bone grafting materials play a significant role in various medical applications involving bone regeneration and repair. Their ability to mimic the properties of natural bone and promote the healing process has contributed to their growing relevance. While calcium-phosphates and their composites with various polymers and biopolymers are widely used in clinical and experimental research, the diverse range of available polymer-based materials poses challenges in selecting the most suitable grafts for successful bone repair. This review aims to address the fundamental issues of bone biology and regeneration while providing a clear perspective on the principles guiding the development of synthetic materials. In this study, we delve into the basic principles underlying the creation of synthetic bone composites and explore the mechanisms of formation for biologically important complexes and structures associated with the various constituent parts of these materials. Additionally, we offer comprehensive information on the application of biologically active substances to enhance the properties and bioactivity of synthetic bone grafting materials. By presenting these insights, our review enables a deeper understanding of the regeneration processes facilitated by the application of synthetic bone composites.

A New Biomaterial Derived from Aloe vera-Acemannan from Basic Studies to Clinical Application

Aloe vera is a kind of herb rich in polysaccharides. Acemannan (AC) is considered to be a natural polysaccharide with good biodegradability and biocompatibility extracted from Aloe vera and has a wide range of applications in the biomedical field due to excellent immunomodulatory, antiviral, antitumor, and tissue regeneration effects. In recent years, clinical case reports on the application of AC as a novel biomedical material in tissue regenerative medicine have emerged; it is mainly used in bone tissue engineering, pulp-dentin complex regeneration engineering, and soft tissue repair, among other operations. In addition, multiple studies have proved that the new composite products formed by the combination of AC and other compounds have excellent biological and physical properties and have broader research prospects. This paper introduces the preparation process, surface structure, and application forms of AC; summarizes the influence of acetyl functional group content in AC on its functions; and provides a detailed review of the functional properties, laboratory studies, clinical cutting-edge applications, and combined applications of AC. Finally, the current application status of AC from basic research to clinical treatment is analyzed and its prospects are discussed.

Aloe vera-Based Hydrogels for Wound Healing: Properties and Therapeutic Effects

Aloe vera-based hydrogels have emerged as promising platforms for the delivery of therapeutic agents in wound dressings due to their biocompatibility and unique wound-healing properties. The present study provides a comprehensive overview of recent advances in the application of Aloe vera-based hydrogels for wound healing. The synthesis methods, structural characteristics, and properties of Aloe vera-based hydrogels are discussed. Mechanisms of therapeutic agents released from Aloe vera-based hydrogels, including diffusion, swelling, and degradation, are also analyzed. In addition, the therapeutic effects of Aloe vera-based hydrogels on wound healing, as well as the reduction of inflammation, antimicrobial activity, and tissue regeneration, are highlighted. The incorporation of various therapeutic agents, such as antimicrobial and anti-inflammatory ones, into Aloe vera-based hydrogels is reviewed in detail. Furthermore, challenges and future prospects of Aloe vera-based hydrogels for wound dressing applications are considered. This review provides valuable information on the current status of Aloe vera-based hydrogels for the delivery of therapeutic agents in wound dressings and highlights their potential to improve wound healing outcomes.

Effects of ceramic additives and bioactive coatings on the degradation of polylactic acid-based bone scaffolds under hydrolytic conditions

Polylactic acid (PLA) has been extensively used for the manufacturing of scaffolds in bone tissue engineering applications. Due to the low hydrophilicity and the acidic degradation process of this biomaterial, different strategies have been proposed to increase the biofunctionality of the support structure. The use of ceramic particles is a generally preferred option to increase the osteoconductivity of the base material, while acting as buffers to maintain the pH level of the surroundings tissues. Surface modification is another approach to overcome the limitations of PLA for tissue engineering applications. In this work, the degradation profile of 3D-printed PLA scaffolds containing beta-tricalcium phosphate (β-TCP) and calcium carbonate (CaCO3 ) particles has been studied under hydrolytic conditions. Composite samples treated with plasma and coated with Aloe vera extracts were also studied to evaluate the effect of this surface modification method. The characterization of the 3D structures included its morphological, calorimetric and mechanical evaluation. According to the results obtained, the proposed composite scaffolds allowed an adequate maintenance of the pH level of the surrounding medium, with no effects observed on the morphology and mechanical properties of these structures. Hence, these samples showed potential to be further investigated as candidates for bone tissue regeneration.

The Therapeutic Potential of Plant Polysaccharides in Metabolic Diseases

Plant polysaccharides (PPS) composed of more than 10 monosaccharides show high safety and various pharmacological activities, including immunoregulatory, antitumor, antioxidative, antiaging, and other effects. In recent years, emerging evidence has indicated that many PPS are beneficial for metabolic diseases, such as cardiovascular disease (CVD), diabetes, obesity, and neurological diseases, which are usually caused by the metabolic disorder of fat, sugar, and protein. In this review, we introduce the common characteristics and functional activity of many representative PPS, emphasize the common risks and molecular mechanism of metabolic diseases, and discuss the pharmacological activity and mechanism of action of representative PPS obtained from plants including Aloe vera, Angelica sinensis, pumpkin, Lycium barbarum, Ginseng, Schisandra chinensis, Dioscorea pposite, Poria cocos, and tea in metabolic diseases. Finally, this review will provide directions and a reference for future research and for the development of PPS into potential drugs for the treatment of metabolic diseases.

Aloe vera protects against fluoride-induced teratogenic effects during pre- and postnatal development in mice

Pregnancy and feto-gestational toxicities on exposure to fluoride and its possible amelioration on co-administration with aloe vera were studied in pregnant Swiss albino mice. Once the confirmed pregnancy was tested, animals were equally divided into four groups as follows: group I was given no treatment and served as control, and groups II and III were administered with 100 and 300 ppm sodium fluoride, respectively, while group IV was co- administered aloe vera (300 mg/kg bw) along with sodium fluoride (300 ppm) daily for 14 days prior to gestation and continued till the 18th day of gestation. Animals were sacrificed on the 19th day of gestation for prenatal observations. Maternal body weight, the gravid uterine weight, number of corpora lutea in both the ovaries, number of implantations and resorptions, number of live (mature and immature) fetuses, and number of dead fetuses were examined in each dam. The treatment continued in another set of animals till the completion of the weaning period to observe postnatal changes due to test substances on the mother and pups. Sodium fluoride-treated animals showed morphometric and skeletal changes which were more pronounced in the high-dose group showing significantly decreased body weight gain in pregnant mothers and dead/immature fetuses. Morphometric changes included open eyelids, limb defects, wrinkles on the whole body, anophthalmia, pulmonary edema, enlarged esophagus, and decreased body weight of fetuses and pups. Alizarin-prepared skeletal structures of fetuses of such female mice showed delayed ossification or bending in the number of bones of skull, thoracic, and limb regions. However, concomitant exposure to sodium fluoride and aloe vera in treated animals led to a marked improvement in all the prenatal and postnatal variables. The study suggests that sodium fluoride at high concentrations may be teratogenic while co-administration of aloe vera during fluoride exposure might be beneficial in reducing these toxic effects. The use of aloe vera as a preventive agent or as a complimentary agent is thus recommended following fluoride exposure through the oral route.

Aloe vera incorporated starch-64S bioactive glass-quail egg shell scaffold for promotion of bone regeneration

Simultaneous promotion of osteoconductive and osteoinductive characteristics through combining bioactive glasses with natural polymers is still a challenge in bone tissue engineering. Starch, 64S bioactive glass (BG), aloe vera (AV) and quail eggshell powder (QE) were utilized to achieve biodegradable, bioactive, biocompatible and mechanically potent multifunctional scaffolds, using freeze-drying mechanism. Cell viability for starch-BG-AV-QE scaffolds at 3 and 7 day intervals was reported to be over 95 %. Acridine orange staining was employed to study live/dead cells cultured on the scaffolds. The high sufficiency of starch-BG-AV-QE scaffolds in osteogenic differentiation and extracellular matrix mineralization was confirmed through alkaline phosphatase activity and alizarin red staining assessments after 7 and 14 days of cell culture. High compressive strength, managed biodegradability and expression of osteocalcin and osteopontin as late markers of osteogenic differentiation were also reached in the range of 30-75 % for starch-BG-AV-QE scaffolds. Hence, starch-BG-AV-QE scaffolds with ideal physico-mechanical and biological characteristics can be considered as promising candidates for promotion of bone regeneration.

The effect of acemannan in implant placement with simultaneous guided bone regeneration in the aesthetic zone: a randomized controlled trial

Acemannan, a linear polysaccharide produced by Aloe vera, has been shown to have important biological effects promoting wound healing and tissue regeneration. The aim of this randomized clinical trial was to investigate the impact of acemannan in guided bone regeneration (GBR) with simultaneous implant placement. Twenty patients were randomly allocated to a test group (deproteinized bovine bone with particulate acemannan (mean size 32.45 μm)) and a control group (deproteinized bovine bone only). Twenty implants were placed with simultaneous GBR. Radiographic measurements were conducted on cone beam computed tomography (CBCT) scans immediately post-surgery and at 3 and 6 months. Vertical and horizontal dimensions of the buccal bone were measured at the implant platform (0) and at points 2, 4, 6, and 8 mm apically. The dimensional reduction of vertical and horizontal buccal bone was significantly smaller in the test group at 3 months postoperative (P < 0.05) at every position measured (0, 2, 4, 6, 8 mm), but the difference was not statistically significant at 6 months. Acemannan was found to be a safe and predictable biomaterial for GBR, which resulted in enhanced dimensional stability of the regenerated tissue at 3 months. However, these results were not replicated at 6 months. Further studies are required to document the long-term efficacy and potential of acemannan use as a supplement in bone regeneration.

Molecular mechanisms and associated cell signalling pathways underlying the anticancer properties of phytochemical compounds from Aloe species (Review)

Naturally occurring components from various species of Aloe have been used as traditional folk medicine since the ancient times. Over the last few decades, the therapeutic effects of extracts and phytochemical compounds obtained from Aloe vera have been proven in preclinical and clinical studies. Recently, compounds from other Aloe species apart from Aloe vera have been investigated for the treatment of different diseases, with a particular focus on cancer. In the present review, the effects of phytochemical compounds obtained from different Aloe species are discussed, with a specific focus on the effects on cell signalling in cancer and normal cells, and their selectivity and efficacy. This information will be useful for the application of Aloe-derived compounds as therapeutic agents, either alone or in combination with other standard drugs for cancer treatment.

Natural medicine delivery from biomedical devices to treat bone disorders: A review

With an increasing life expectancy and aging population, orthopedic defects and bone graft surgeries are increasing in global prevalence. Research to date has advanced the understanding of bone biology and defect repair mechanism, leading to a marked success in the development of synthetic bone substitutes. Yet, the quest for functionalized bone grafts prompted the researchers to find a viable alternative that regulates cellular activity and supports bone regeneration and healing process without causing serious side-effects. Recently, researchers have introduced natural medicinal compounds (NMCs) in bone scaffold that enables them to release at a desirable rate, maintains a sustained release allowing sufficient time for tissue in-growth, and guides bone regeneration process with minimized risk of tissue toxicity. According to World Health Organization (WHO), NMCs are gaining popularity in western countries for the last two decades and are being used by 80% of the population worldwide. Compared to synthetic drugs, NMCs have a broader range of safety window and thus suitable for prolonged localized delivery for bone regeneration. There is limited literature focusing on the integration of bone grafts and natural medicines that provides detailed scientific evidences on NMCs, their toxic limits and particular application in bone tissue engineering, which could guide the researchers to develop functionalized implants for various bone disorders. This review will discuss the emerging trend of NMC delivery from bone grafts, including 3D-printed structures and surface-modified implants, highlighting the significance and potential of NMCs for bone health, guiding future paths toward the development of an ideal bone tissue engineering scaffold. STATEMENT OF SIGNIFICANCE: To date, additive manufacturing technology provids us with many advanced patient specific or defect specific bone constructs exhibiting three-dimensional, well-defined microstructure with interconnected porous networks for defect-repair applications. However, an ideal scaffold should also be able to supply biological signals that actively guide tissue regeneration while simultaneously preventing post-implantation complications. Natural biomolecules are gaining popularity in tissue engineering since they possess a safer, effective approach compared to synthetic drugs. The integration of bone scaffolds and natural biomolecules exploits the advantages of customized, multi-functional bone implants to provide localized delivery of biochemical signals in a controlled manner. This review presents an overview of bone scaffolds as delivery systems for natural biomolecules, which may provide prominent advancement in bone development and improve defect-healing caused by various musculoskeletal disorders.

Acemannan-induced tooth socket healing: A 12-month randomized controlled trial

Background/purpose

Natural compounds have become alternatives for bone regeneration. Acemannan, the main polysaccharide extracted from Aloe vera, has been demonstrated as a promising osteoinductive material in vitro and in vivo. This clinical study investigated the effect of acemannan on tooth socket healing.

Materials and methods

Thirty-five otherwise healthy patients, 18–25 years old and diagnosed with horizontal or vertical partial impaction of the lower third molars, were enrolled in this randomized controlled trial. After removing the teeth, the sockets randomly received one of the following treatments: spontaneous blood-clotting (control), 20 mg acemannan sponge, or 50 mg acemannan sponge. Cone-beam computed tomography of the mandible was performed immediately (baseline), and at 3-, 6-, and 12-months postoperatively; the data were analyzed using the OsiriX MD program. Bone healing in the socket was determined measuring the socket volume. One-way ANOVA was used to analyze the differences within each group and between groups.

Results

Thirty-five patients with 43 partially impacted lower third molars participated in this study. No patients exhibited alveolar osteitis or secondary infection. Compared with baseline, all groups showed significant reduction in socket volume at all observation time-points (p < 0.05). The 50 mg acemannan group had a significantly greater reduction in socket volume compared with the control at all postoperative time-points (p < 0.05). The 20 mg group had a significantly greater reduction in socket volume compared with the control at 3-months postoperatively (p < 0.05).

Conclusion

We conclude that acemannan increases bone healing at 3-, 6-, and 12-months after removal of partially impacted mandibular third molars.

Acemannan induces rapid early osseous defect healing after apical surgery: A 12-month follow-up of a randomized controlled trial

Background/purpose

Acemannan is an osteoinductive material. This study's objective was to compare the outcomes of bone defect healing using 3-dimensional images after apical surgery with or without adding acemannan sponges.

Materials and methods

Twenty-two anterior teeth from 9 males and 13 females requiring apical surgery were included in this randomized controlled trial. Post-surgery, the bone defects were randomly divided into three groups: blood clot control, 5-, or 10-mg acemannan sponge groups. CBCT scans were taken immediately (baseline), 3-, 6-, and 12-month post-surgery. Sagittal serial sections (1 mm thick slices parallel to the long axis of the tooth) of the defect image were created. The defect boundary was located and the total bone defect volume (BDV) was calculated from the sum of the volume of the serial defect sections. The bone healing was assessed by the percentage of total bone defect volume reduction (%ΔBDV). The paired t-test and one-way ANOVA were used to analyze the differences within each group and between groups, respectively.

Results

The baseline mean BDV of the control, 5-, and 10-mg acemannan groups were not significantly different (p > 0.05). After treatment, the mean BDV for each group was reduced in a time-dependent manner. Compared with the control group, the 5- and 10-mg acemannan groups had a significantly greater %ΔBDV (approximately 2- and 1.89-fold) at 3-months post-surgery, respectively (p < 0.05). However, at the 6- and 12- month follow-up, the %ΔBDV was not significantly different between the groups.

Conclusion

These data suggest acemannan enhanced early bone healing after apical surgery.

Natural Medicinal Compounds in Bone Tissue Engineering

Recent advances in 3D printing have provided unprecedented opportunities in bone tissue engineering applications for producing a variety of complex patient-specific implants for the treatment of critical-sized bone defects. Natural medicinal compounds (NMCs) with osteogenic potential can be incorporated into these 3D-printed parts to improve bone formation and therefore enhance implant performance. Using NMCs to treat bone-related disorders may prove to be a healthy preventive choice as they are considered safe, have lesser or no side effects, and are more suitable for prolonged use than synthetic drugs. In this review paper, the current challenges of bone tissue engineering are addressed briefly, highlighting the immense potential of NMCs integrated within tissue engineering scaffolds for orthopedic and dental applications.

Effects of Aloe Vera Gel Extract in Doped Hydroxyapatite-Coated Titanium Implants on in Vivo and in Vitro Biological Properties

Hydroxyapatite-coated titanium alloys have been a popular choice as bone implants for load-bearing applications for the compositional similarity of hydroxyapatite to natural bone. The limited osteoinductive properties exhibited by the hydroxyapatite (HA) coatings have led to the incorporation of growth factor or dopants for improved osseointegration. This study aims to investigate the effects of a naturally occurring aloe vera gel extract, acemannan, in doped hydroxyapatite coatings on the in vitro osteoblast cell viability and in vivo new bone formation in a rat distal femur model. Silver oxide and silica-doped hydroxyapatite coatings were developed by the induction plasma spray coating method on Ti alloys to introduce antibacterial properties along with induction of angiogenic properties, respectively. The doped coating was further consecutively dip coated with acemannan to analyze its effects on the in vivo early stage osseointegration and chitosan to control the burst release of the acemannan from the calcium phosphate matrix. The results show controlled release of acemannan from the chitosan coatings, with enhanced osteoblast cell viability by the incorporation of acemannan in vitro. Improved osseointegration with a seamless implant interface and improved new bone formation was noted by the acemannan and chitosan coating in vivo, 5 weeks after implantation. Our results demonstrate the efficacy of a combination of natural medicine and naturally occurring polymer in a doped hydroxyapatite-coated titanium implant on the bone tissue regeneration for load-bearing orthopedic applications.

Extraction, Purification, Structural Characteristics, Biological Activities and Pharmacological Applications of Acemannan, a Polysaccharide from Aloe vera: A Review

Aloe vera is a medicinal plant species of the genus Aloe with a long history of usage around the world. Acemannan, considered one of the main bioactive polysaccharides of Aloe vera, possesses immunoregulation, anti-cancer, anti-oxidation, wound healing and bone proliferation promotion, neuroprotection, and intestinal health promotion activities, among others. In this review, recent advancements in the extraction, purification, structural characteristics and biological activities of acemannan from Aloe vera were summarized. Among these advancements, the structural characteristics of purified polysaccharides were reviewed in detail. Meanwhile, the biological activities of acemannan from Aloe vera determined by in vivo, in vitro and clinical experiments are summarized, and possible mechanisms of these bioactivities were discussed. Moreover, the latest research progress on the use of acemannan in dentistry and wound healing was also summarized in details. The structure-activity relationships of acemannan and its medical applications were discussed. Finally, new perspectives for future research work on acemannan were proposed. In conclusion, this review summarizes the extraction, purification, structural characteristics, biological activities and pharmacological applications of acemannan, and provides information for the industrial production and possible applications in dentistry and wound healing in the future.

Improved Multicellular Response, Biomimetic Mineralization, Angiogenesis, and Reduced Foreign Body Response of Modified Polydioxanone Scaffolds for Skeletal Tissue Regeneration

The potential of electrospun polydioxanone (PDX) mats as scaffolds for skeletal tissue regeneration was significantly enhanced through improvement of the cell-mediated biomimetic mineralization and multicellular response. This was achieved by blending PDX ( i) with poly(hydroxybutyrate- co-valerate) (PHBV) in the presence of hydroxyapatite (HA) and ( ii) with aloe vera (AV) extract containing a mixture of acemannan/glucomannan. In an exhaustive study, the behavior of the most relevant cell lines involved in the skeletal tissue healing cascade, i.e. fibroblasts, macrophages, endothelial cells and preosteoblasts, on the scaffolds was investigated. The scaffolds were shown to be nontoxic, to exhibit insignificant inflammatory responses in macrophages, and to be degradable by macrophage-secreted enzymes. As a result of different phase separation in PDX/PHBV/HA and PDX/AV blend mats, cells interacted differentially. Presumably due to varying tension states of cell-matrix interactions, thinner microtubules and significantly more cell adhesion sites and filopodia were formed on PDX/AV compared to PDX/PHBV/HA. While PDX/PHBV/HA supported micrometer-sized spherical particles, nanosized rod-like HA was observed to nucleate and grow on PDX/AV fibers, allowing the mineralized PDX/AV scaffold to retain its porosity over a longer time for cellular infiltration. Finally, PDX/AV exhibited better in vivo biocompatibility compared to PDX/PHBV/HA, as indicated by the reduced fibrous capsule thickness and enhanced blood vessel formation. Overall, PDX/AV blend mats showed a significantly enhanced potential for skeletal tissue regeneration compared to the already promising PDX/PHBV/HA blends.