Elevated fluid and glycosaminoglycan content in the Achilles tendon contribute to higher intratendinous pressures:Implications for Achilles tendinopathy

Background:Tendinopathy alters the compositional properties of the Achilles tendon by increasing fluid and glycosaminoglycan content.It has been speculated that these changes may affect intratendinous pressure,but the extent of this relationship remains unclear.Therefore,we aimed to investigate the impact of elevated fluid and glycosaminoglycan content on Achilles tendon intratendinous pressure and to determine whether hyaluronidase(HYAL) therapy can intervene in this potential relationship.Methods:Twenty paired fresh-frozen cadaveric Achilles tendons were mounted in a tensile-testing machine and loaded up to 5% strain.Intratendinous resting(at 0% strain) and dynamic pressure(at 5% strain) were assessed using the microcapillary infusion technique.First,intratendinous pressure was measured under native conditions before and after infusion of 2 mL physiological saline.Next,80 mg of glycosaminoglycans were administered bilaterally to the paired tendons.The right tendons were additionally treated with 1500 units of HYAL.Finally,both groups were retested,and the glycosaminoglycan content was analyzed.Results:It was found that both elevated fluid and glycosaminoglycan content resulted in higher intratendinous resting and dynamic pressures(p <0.001).HYAL treatment induced a 2.3-fold reduction in glycosaminoglycan content(p=0.002) and restored intratendinous pressures.Conclusion:The results of this study demonstrated that elevated fluid and glycosaminoglycan content in Achilles tendinopathy contribute to increased intratendinous re sting and dynamic pressures,which can be explained by the associated increased volume and reduced permeability of the tendon matrix,respectively.HYAL degrades glycosaminoglycans sufficiently to lower intratendinous pressures and may,therefore,serve as a promising treatment.

Evaluation of Glycosaminoglycan in the Lumbar Disc Using Chemical Exchange Saturation Transfer MR at 3.0 Tesla:Reproducibility and Correlation with Disc Degeneration

Objective This study aims to explore the clinical applicability and relevance of giycosaminoglycan Chemical Exchange Saturation Transfer （gagCEST） for intervertebral disc. Methods 25 subjects ranging in age from 24 yrs to 74 yrs were enrolled, gagCEST was acquired using a single-slice TSE sequence on a 3T. Saturation used a continuous rectangular RF pulse with B1=0.8 I^T and a fixed duration time =1100 ms. Sagittal image was obtained firstly without saturation pulse, and then saturated images were acquired at 52 offsets ranging from ＋0.i25 to ＋_7 parts per million （ppm）. MR T2 relaxivity map was acquired at the identical location. Six subjects were scanned twice to assess scan-rescan reproducibility. Results GagCEST intraclass correlation coefficient （ICC） of six subjects was 0.759 for nucleus pulposus （NP） and 0.508 for annulus fibrosus （AF）. Bland-Altman plots showed NP had a mean difference of 0.10% （95% limits of agreement： -3.02% to 3.22%）; while that of AF was 0.34% （95% limits of agreement： -2.28% to 2.95%）. For the 25 subjects, gag CEST in NP decreased as disc degeneration increased, with a similar trend to T2 relaxivity. Gag CEST of AF showed a better correlation with disc degeneration than T2 relaxivity. Conclusion GagCEST in NP and AF decreased as disc degeneration increased, while gagCEST in AF showed a better correlation than T2 relaxivity.

Glycosaminoglycan remodeling during diabetes and the role of dietary factors in their modulation

Glycosaminoglycans(GAGs) play a significant role in various aspects of cell physiology.These are complex polymeric molecules characterized by disaccharides comprising of uronic acid and amino sugar.Compounded to the heterogeneity,these are variously sulfated and epimerized depending on the class of GAG.Among the various classes of GAG,namely,chondroitin/dermatan sulfate,heparin/heparan sulfate,keratan sulfate and hyaluronic acid(HA),only HA is non-sulfated.GAGs are known to undergo remodeling in various tissues during various pathophysiological conditions,diabetes mellitus being one among them.These changes will likely affect their structure thereby impinging on their functionality.Till date,diabetes has been shown to affect GAGs in organs such as kidney,liver,aorta,skin,erythrocytes,etc.to name a few,with deleterious consequences.One of the mainstays in the treatment of diabetes is though dietary means.Various dietary factors are known to play a significant role in regulating glucose homeostasis.Furthermore,in recent years,there has been a keen interest to decipher the role of dietary factors on GAG metabolism.This review focuses on the remodeling of GAGs in various organs during diabetes and their modulation by dietary factors.While effect of diabetes on GAG metabolism has been worked out quite a bit,studies on the role of dietary factors in their modulation has been few and far between.We have tried our best to give the latest reports available on this subject.

Enhancement of matrix metalloproteinases 2 and 9 accompanied with neurogenesis following collagen glycosaminoglycan matrix implantation after surgical brain injury

Surgical brain injury may result in irreversible neurological deficits. Our previous report showed that partial regeneration of a traumatic brain lesion is achieved by implantation of collagen glycosaminoglycan（CGM）. Matrix metalloproteinases（MMPs） may play an important role in neurogenesis but there is currently a lack of studies displaying the relationship between the stimulation of MMPs and neurogenesis after collagen glycosaminoglycan implantation following surgical brain trauma. The present study was carried out to further examine the expression of MMP2 and MMP9 after implantation of collagen glycosaminoglycan（CGM） following surgical brain trauma. Using the animal model of surgically induced brain lesion, we implanted CGM into the surgical trauma. Rats were thus divided into three groups：（1） sham operation group： craniotomy only;（2） lesion（L） group： craniotomy ＋ surgical trauma lesion;（3） lesion ＋ CGM（L ＋ CGM） group： CGM implanted following craniotomy and surgical trauma lesion. Cells positive for SOX2（marker of proliferating neural progenitor cells） and matrix metalloproteinases（MMP2 and MMP9） in the lesion boundary zone were assayed and analyzed by immunofluorescence and ELISA commercial kits, respectively. Our results demonstrated that following implantation of CGM after surgical brain trauma, significant increases in MMP2^＋/SOX2^＋ cells and MMP9^＋/SOX2^＋ cells were seen within the lesion boundary zone in the L ＋ CGM group. Tissue protein concentrations of MMP2 and MMP9 also increased after CGM scaffold implantation. These findings suggest that implantation of a CGM scaffold alone after surgical brain trauma can enhance the expression of MMP2 and MMP9 accompanied by neurogenesis.

Assessment of Glycosaminoglycan Content of Lumbar Intervertebral Discs in Patients with Radiculopathy

Objective: To assess glycosaminoglycan (GAG) content of lumbar intervertebral discs (IVDs) in patients with radiculopathy compared with healthy volunteers with glycosaminoglycan chemical exchange saturation transfer (gagCEST). Methods: The lumbar spines of 15 patients with radiculopathy (9 women, 6 men;mean age 45 years;range: 19 - 80 years) and 13 healthy controls (10 women, 3 men;mean age 29 years;range: 19 - 38 years) without lumbar back pain or previous spine surgery were examined at a 3 Tesla (T) magnetic resonance imaging (MRI) scanner in this prospective study. The MRI protocol included standard morphological, sagittal, and transverse T2-weighted (T2w) images of the five lumbar IVDs (L1-S1) to assess Pfirrmann score and to detect disc disorders according to the Combined Task Force classification. To analyze biochemically the lumbar IVDs, a gagCEST sequence was applied to measure the GAG content of the nucleus pulposus (NP) and annulus fibrosus (AF). Results: Patients with radiculopathy indicated significantly lower gagCEST values in NP than healthy volunteers (2.82% &plusmn;3.12% vs. 4.09% &plusmn;2.25%, P = 0.017). The GAG content of AF showed no significant difference between volunteers and patients (2.66% &plusmn;2.01% vs. 1.92% &plusmn;2.56%;P = 0.175). Conclusions. Patients with radiculopathy presented with lower GAG values than healthy volunteers in NP, indicating an association between pain and IVD degeneration. gagCEST of lumbar IVDs is a powerful, non-invasive tool to investigate early disc degeneration, which we could demonstrate in the NP in our study collective.

Preparation and Biocompatibility of Porous Poly(vinylalcohol)-Glycosaminoglycan-Collagen Scaffold

This paper aims to prepare a PVA-GAG-COL composite with polyvinyl alcohol (PVA), glycosaminoglycan (GAG) and collagen (COL) by the method of freeze drying and to investigate the feasibility as a tissue engineering scaffold for tissue or organ repairing. In this study, SEM was used to observe the morphology. Biocompatibility was tested by cell culture with the extracted fluid of composite materials. Different proportional scaffolds could be obtained with different concentrations and alcoholysis degree of PVA. Different proportional scaffolds also had different porous structures. SEM proved that large amount of porous structure could be formed. Biocompatibility test showed that the extracted fluid of composite materials was nontoxic, which could promote the adhesion and proliferation of the fibroblast. Fibroblast could grow on the scaffold normally.A porous scaffold for tissue engineering with high water content can be fabricated by PVA, GAG and COL, which has excellent cell biocompatibility. The porous structure shows potential in tissue engineering and cell culture.

Polyvinyl Alcohol-Collagen Composite with Glycosaminoglycan as Scaffolds for Tissue Engineering

The aim of this study is to prepare a PVA-GAG-COL composite material by polyvinyl alcohol (PVA),glycosaminoglycan (GAG) and collagen (COL),and to investigate the feasibility of serving as a scaffold for tissue engineering. PVA was blended with various amounts of GAG and COL. Different proportional scaffolds could be obtained with different molecular weight and alcoholysis degree of PVA and different amounts of GAG,which exhibited high water content (60%-95%) and showed different inner configuration with swelling ratio (120%-620%). SEM proved that different composite materials had different porous structures.

Pores Created by Laser Surface Modification of Poly(vinylalcohol)-Collagen with Glycosaminoglycan Scaffold for Cell Culture in Tissue Engineering

A PVA-GAG-COL composite scaffold is fabricated by polyvinyl alcohol （PVA）, glyeosaminoglycan （GAG） and collagen （COL）. Laser surface modification technology is used to make holes on the surface of the scaffolds. Inside and outside interconnection micro-porous structure is obtained. Bioeompatibility test of the scaffolds shows that PVA-GAG-COL scaffold can promote the adhesion and proliferation of the fibroblast. Also, fibroblast can grow normally on the scaffolds with pore diameter from 115 um to 255 um and pore distance from 500 um to 2000 um. PVA-GAG-COL scaffolds possess excellent cell biocompatibility. The porous structure is suitable for cell culture in tissue engineering.

Quantitative detection and comparison of sulfate glycosaminoglycans content in extracellular matrix of in vitro cultured epiphyseal, articular and rib chondrocytes

Objective To establish a method for quantitative detection of the sulfate glycosaminoglycans ( GAG) content in extracellular matrix of in vitro cultured chondrocytes so as to evaluate the biological characteristics of epiphyseal, articular and rib chondrocytes. Methods Sulfate GAG content in extracellular matrix of three chondrocytes was measured by the modified dimethylmethylene blue (DMB) method. The changes of the toluidine blue (TB) stain of chondrocytes were observed by light microscope. Results Primary chondrocytes had the highest content of sulfate GAG in the extracellular matrix, ie, epiphyseal chondrocytes reached ( 70. 12 ± 7. 72 )μg/cm2, articular chondrocytes (92.00 ± 10.15) μg/cm2 and rib chondrocytes (80.61 ± 11. 40) μg/cm2, respectively. On the third pasage chondrocytes, epiphyceal chondrocytes decreased to (53.27 ± 9. 50 ) μg/cm2, articular chondrocytes to (63.88 ± 11.92) μg/cm2 and rib chondrocytes to (58.94 ±8.21) μg/cm2, respectively. The change of TB in every passage

Anti-Inflammatory Glycosaminoglycan Oligosaccharides from Colwellia psychrerythraea 34H Capsule:Synthesis and Biological Evaluation

Capsular polysaccharides(CPS)of Colwellia psychrerythraea 34H consist of linear tetrasaccharides repeating units in a glycosaminoglycan-like fashion.Their biological function is likely involved in the cold adaptation of microbial organisms.The low availability of these glycosaminoglycan structures greatly limits the study of their functions and biological activities.Here,an efficient semisynthetic strategy for CPS tetrasaccharide derivatives is achieved by using disaccharide units degraded from hyaluronic acids.This new synthetic process is suitable for largescale preparation,and several rare tetrasaccharide derivatives containing GalA-GalNAc were readily obtained in high yields.Biological evaluation of their anti-inflammatory effects demonstrated that these CPS tetrasaccharides effectively attenuated the lipopolysaccharide-induced sepsis and acute lung injury by decreasing macrophage infiltration and secretion of microphage-related cytokines in mice.All these results suggest that this new type of CPS tetrasaccharide can be developed as an anti-inflammation agent.

Research progress on the skincare efficacy of sulfated glycosaminoglycans

With the improvement of consumers’scientific skin care consciousness,skin problems-oriented efficacy skin care and precise skin care methods have become the future development trend.Glycosaminoglycans are long,linear polysaccharides comprised of repeated disaccharide units,which are highly expressed endogenously in the skin.They are commonly present in skin cells,cell surface and extracellular matrix,with pleiotropic biological function.In addition to hyaluronic acid,the sulfated glycosaminoglycans heparin,heparan sulfate,dermatan sulfate and chondroitin sulfate play an important role in anti-wrinkle,firming,soothing,and improving microvascular circulation,but are still in the research and development stage in cosmetics.This paper summarizes the skincare mechanism of sulfated glycosaminoglycans,and demonstrates the potential of sulfated glycosaminoglycans as functional raw materials in cosmetics.

Quantitatively relating magnetic resonance T_(1)and T_(2)to glycosaminoglycan and collagen concentrations mediated by penetrated contrast agents and biomacromolecule-bound water

Magnetic resonance imaging(MRI)is a promising non-invasive method to assess cartilage regeneration based on the quantitative relationship between MRI features and concentrations of the major components in the extracellular matrix(ECM).To this end,in vitro experiments are performed to investigate the relationship and reveal the underlying mechanism.A series of collagen(COL)and glycosaminoglycan(GAG)solutions at different concentrations are prepared,and T_(1)and T_(2)relaxation times are measured with or without a contrast agent(Gd-DTPA2−)by MRI.Fourier transform infrared spectrometry is also used to measure the contents of biomacromolecule-bound water and other water,allowing theoretical derivation of the relationship between biomacromolecules and the resulting T_(2)values.It has been revealed that the MRI signal in the biomacromolecule aqueous systems is mainly influenced by the protons in hydrogens of biomacromolecule-bound water,which we divide into inner-bound water and outer-bound water.We have also found that COL results in higher sensitivity of bound water than GAG in T_(2)mapping.Owing to the charge effect,GAG regulates the penetration of the contrast agent during dialysis and has a more significant effect on T_(1)values than COL.Considering that COL and GAG are the most abundant biomacromolecules in the cartilage,this study is particularly useful for the real-time MRI-guided assessment of cartilage regeneration.A clinical case is reported as an in vivo demonstration,which is consistent with our in vitro results.The established quantitative relation plays a critical academic role in establishing an international standard ISO/TS24560-1:2022‘Clinical evaluation of regenerative knee articular cartilage using delayed gadolinium-enhanced MRI of cartilage(dGEMRIC)and T_(2)mapping’drafted by us and approved by International Standard Organization.

Extraction and quantification of sulfated glycosaminoglycan content in five different aquatic species of Malaysia

Objective:To extract,characterize and quantify glycosaminoglycans(GAGs)from the body of cuttlefish,tennis-ball sea cucumber,shrimp,seabass and fresh water fish Nile tilapia.Methods:The extracted crude powder was evaluated for the content of GAGs.The qualitative analysis of sulfated pattern and other important functional groups related with GAGs were explained in the form of Fourier transform infra-red spectroscopy data.Proteins and nucleic acid in the crude extract were determined by the ultraviolet spectrophotometer,while the quantification of total sulfated GAGs and estimation of N-sulfated and O-sulfated GAGs in the crude mixture were performed by using Blyscan kit.Results:The sulfated pattern and other important functional groups related with GAGs were intercepted in Fourier transform infrared analysis.Blyscan quantification method reported that a rare variety of sea cucumber(tennis-ball sea cucumber)emerged as a rich source of GAGs with high values of both N-sulfated and O-sulfated GAGs in comparison to its other counterparts.Conclusions:Findings in this study point out the potential of tennis-ball sea cucumber,a rare variety of sea cucumber to act as an alternative source for GAG extraction for commercial purpose.

液相色谱串联质谱检测尿黏多糖在黏多糖贮积症患者诊断与随访中的应用

目的运用液相色谱串联质谱(LC-MS/MS)技术建立尿液中硫酸软骨素(CS)、硫酸皮肤素(DS)和硫酸乙酰肝素(HS)含量的检测方法,探究该方法在黏多糖贮积症(MPS)患者诊断及治疗随访中的应用。方法收集20例MPS患儿及37例正常儿童尿液样本,测定尿液中CS、DS和HS等浓度。尿样氮气吹干,盐酸甲醇衍生化,再次氮气吹干,复溶后LC-MS/MS分析;评价方法的线性、定量限、精密度、加样回收率和基质效应。结果LC-MS/MS检测CS、DS和HS的线性均大于0.99。CS、DS和HS的定量下限依次为:0.5、1.0和1.0 mg/L。批内不精密度为1.9%~10.4%,批间不精密度为2.6%~9.8%。加标回收率为85.6%~110.4%,相对基质效应为84.9%~115.5%。CS、DS和HS在正常儿童尿液中呈正态分布,以x+1.64 SD计算正常儿童尿液中的参考区间上限,分别为16.5、1.8、1.4 mg/mmol。通过分析MPS患儿尿液黏多糖特点,LC-MS/MS法能有效检出MPS I、MPSⅡ、MPSⅢ和MPSⅥ等MPS患儿。已接受造血干细胞移植的MPSⅠ和MPSⅡ患儿尿DS、HS水平降低。结论LC-MS/MS检测尿黏多糖性能良好,有望用于MPS患者的精准诊断和治疗随访监测。

硫酸软骨素蛋白多糖在脊髓损伤中的研究进展

硫酸软骨素蛋白多糖(chondroitin sulfate proteoglycans,CSPGs)是中枢神经系统细胞外基质的组成部分,在中枢神经系统发育、正常维持及病理过程中都发挥着关键的作用。脊髓损伤后,损伤部位CSPGs的表达明显上调,这主要源于病变部位活化的星形胶质细胞。CSPGs的上调会限制脊髓损伤部位的轴突再生、传导和再髓鞘化,并且可以促进脊髓损伤中的炎症反应,不利于脊髓损伤后神经功能恢复。因此,抑制CSPGs可能是促进脊髓损伤后轴突再生和功能恢复的有效治疗方法。本文对CSPGs在脊髓损伤中的研究现状进行综述。

Effects of adeno-associated virus (AAV) of transforming growth factors β_1 and β_3 (TGFβ_(1,3)) on promoting synthesis of glycosaminoglycan and collagen type II of dedifferentiated nucleus pulposus (NP) cells

The effects of AAV-TGF beta_1 and AAV-TGF beta_3 on promoting synthesis ofglycosaminoglycan and collagen type II of dedifferentiated rabbit lumbar disc NP cells were studiedin this work.The rabbit lumbar disc NP cells were isolated and cultured.The earlier and laterdedifferentiated NP cells were established by subculture.The AAV transfection efficiency todedifferentiated NP cells was analyzed with AAV-EGFP in vitro.After dedifferentiated NP cells weretransfected by AAV-TGFp,or AAV-TGF beta_3,their biological effects on promoting synthesis ofglycosaminoglycan or collagen type II were detected and compared by the methods of 35S incorporationor immunoblotting.The experimental results showed that AAV could transfect efficiently the earlierdedifferentiated NP cells,but its transfection rate was shown to be at a low level to the laterdedifferentiated NP cells.Both AAV-TGF beta_1,and AAV-TGF beta_3 could promote the earlierdedifferentiated NP cells to synthesize glycosaminoglycan and collagen type II,and the effect ofAAV-TGFp,was better than that of AAV-TGF beta_3.For the later dedifferentiated NP cells,the AAV-TGFbeta_3 could promote their synthesis,but AAV-TGFp,could slightly inhibit theirsynthesis.Therefore,AAV-TGFp,and AAV-TGF beta_3 could be used for the earlier dedifferentiated NPcells,and the TGF beta_3 could be used as the objective gene for the later dedifferentiated NPcells.

Glycosaminoglycan Content of the Lateral Compartment Cartilage in Knees Conforming to the Indications for Oxford Medial Unicompartmental Knee Arthroplasty

Background： The quality of the lateral compartment cartilage is important to preoperative evaluation and prognostic prediction of unicompartmental knee arthroplasty （UKA）. Delayed gadolinium-enhanced magnetic resonance imaging of cartilage （dGEMRIC） enables noninvasive assessment of glycosaminoglycan （GAG） content in cartilage. This study aimed to determine the GAG content of the lateral compartment cartilage in knees scheduled to undergo Oxford medial UKA. Methods： From December 2016 to May 2017, twenty patients （20 osteoarthritic knees） conforming to the indications fbr Oxford medial UKA were included as the osteoarthritis （OA） group, and 20 healthy volunteers （20 knees） paired by sex, knee side, age （±3 years）, and body mass index （BMI） （i3 kg/m2） were included as the control group. The GAG contents of the weight-bearing femoral cartilage （wbFC）, the posterior non-weight-bearing femoral cartilage （pFC）, the lateral femoral cartilage （FC）, and tibial cartilage （TC） were detected using dGEMRIC. The dGEMRIC indices （T1Gd） were calculated in the middle three consecutive slices of the lateral compartment. Paired t-tests were used to compare the T1Gd in each region of interest between the OA group and control group. Results： The average age and BMI in the two groups were similar. In the OA group, TIGd of FC and TC was 386.7 ± 50.7 ms and 429.6 ± 59.9 ins, respectively. In the control group, T1Gd of FC and TC was 397.5 ± 52.3 ms and 448.6 ±62.5 ms, respectively. The respective T 1Gd ofwbFC and pFC was 380.0 ± 47.8 ms and 391.0 ± 66.3 ms in the OA group and 400.3 ± 51.5 ms and 393.6 ± 57.9 ms in the control group. Although the T 1Gd ofwbFC and TC tended to be lower in the OA group than the control group, there was no significant difference between groups in the TIGd in any of the analyzed cartilage regions （P value ofwbFC, pFC, FC, and TC was 0.236, 0.857, 0.465, and 0.324, respectively）. Conclusions： The GAG content of the lateral compartment cartilage in knees confonning to indications for Oxford medial UKA is similar with those of age- and BMl-matched participants without OA.

Fabrication and Properties of Poly(vinylalcohol)-glycosaminoglycantype I Collagen Composite Membrane as Tissue Regeneration Scaffolds

The objective of this paper is to design a based on composite membrane with certain mechanical porous polyvinyl alcohol （PVA） strength and biocompatibilities serving as tissue regenerative scaffolds. PVA-glycosaminoglycan （GAG）-type I collagen （COL） composite membrane was fabricated by PVA with different molecular weight （Mw） and alcoholysis degree （AD） being blended with certain amounts of GAG and COL and dried at 38~C for 24 h. The water content of the composite membranes were from 61.9% to 95.1% and swelling ratio ranged from 123.6% to 621.7%. Scanning electron micro- scope （SEM） analysis proved that PVA-GAG-COL composite membrane has porous and homogenous structure. Biocompatibility test results showed that the composite membrane was nontoxic, which could promote adhesion and proliferation of fibroblasts on the com- posite membrane. In conclusion, PVA-GAG-COL composite membrane with high water content and swelling ratio, suitable mechanical strength and good biocompatibility, has potential in tissue engineering and regenerative medicine.

糖胺聚糖在骨组织工程中的应用进展

骨组织缺损是目前最常见的医疗疾病之一。自体骨移植和同种异体骨移植等存在供体不足、移植物免疫反应及移植部位感染等不足,而骨组织工程(BTE)可通过合适的骨替代支架克服目前骨组织重建方法的局限性。骨支架材料应具有生物相容性、生物可再生性和仿生性。天然来源的糖胺聚糖(GAG)可模拟哺乳动物细胞外基质成分,具有稳定和持续释放生长因子、可调的孔隙率、磷酸钙成核位点、一定的黏弹性和保水性。因此,GAG具有调节生物矿化、稳定生长因子、促进细胞黏附及细胞信号转导等功能,可作为一种独特的生物材料广泛用于BTE。

Bioengineered production of glycosaminoglycans and their analogues

Glycosaminoglycans(GAGs)are a class of linear polysaccharides,consisting of alternating disaccharide sequences of uronic acid and hexosamines(or galactose)with and without sulfation.They can interact with various proteins,such as growth factors,receptors and cell adhesion molecules,endowing these with various biological and pharmacological activi-ties.Such activities make GAGs useful in health care products and medicines.Currently,all GAGs,with the exception of hyaluronan,are produced by extraction from animal tissues.However,limited availability,poor control of animal tissues,impurities,viruses,prions,endotoxins,contamination and other problems have increased the interest in new approaches for GAG production.These new approaches include GAGs production by chemical synthesis,chemoenzymatic synthesis and metabolic engineering.One chemically synthesized heparin pentasaccharide,fondaparinux sodium,is in clinical use.Mostly,hyaluronan today is prepared by microbial fermentation,largely replacing hyaluronan from rooster comb.The recent gram scale chemoenzymatic synthesis of a heparin dodecasaccharide suggests its potential to replace currently used animal-sourced low molecular weight heparin(LMWH).Despite these considerable successes,such high-tech approaches still cannot meet worldwide demands for GAGs.This review gives a brief introduction on the manufacturing of unfractionated and low molecular weight heparins,the chemical synthesis and chemoenzymatic synthesis of GAGs and focuses on the progress in the bioengineered preparation of GAGs,particularly heparin.