Fabrication and cell affinity of biomimetic structured PLGA/articular cartilage ECM composite scaffold.

An ideal scaffold for cartilage tissue engineering should be biomimetic in not only mechanical property and biochemical composition, but also the morphological structure. In this research, we fabricated a composite scaffold with oriented structure to mimic cartilage physiological morphology, where natural nanofibrous articular cartilage extracellular matrix (ACECM) was used to mimic the biochemical composition, and synthetic PLGA was used to enhance the mechanical strength of ACECM. The composite scaffold has well oriented structure and more than 89% of porosity as well as about 107 µm of average pore diameter. The composite scaffold was compared with ACECM and PLGA scaffolds. Cell proliferation test showed that the number of MSCs in ACECM and composite scaffolds was noticeably bigger than that in PLGA scaffold, which was coincident with results of SEM observation and cell viability staining. The water absorption of ACECM and composite scaffolds were 22.1 and 10.2 times respectively, which was much higher than that of PLGA scaffolds (3.8 times). The compressive modulus of composite scaffold in hydrous status was 1.03 MPa, which was near 10 times higher than that of hydrous ACECM scaffold. The aforementioned results suggested that the composite scaffold has the potential for application in cartilage tissue engineering.

Hypokalaemia in Sjögren's syndrome: the missing piece.

A 58-year-old Chinese woman with well controlled type 1 diabetes mellitus presented with acute and progressive bilateral lower limb weakness. Investigations revealed severe hypokalaemia (1.3 mmol/L) and hypophosphataemia (<0.32 mmol/L) with rhabdomyolysis and electrocardiogram changes, without other concurrent biochemical abnormalities. Immediate intravenous and oral potassium and phosphate replacement was initiated with objective improvement in weakness with replenished electrolyte levels. Urine studies confirmed renal potassium wasting. Further history revealed frequent dental caries, xerostomia and recent weight loss. A computerised tomography scan showed atrophy of her salivary glands and a skin lesion biopsied by her GP in the past had been histologically characterised as anetoderma. The constellation of these findings and subsequent positive anti-SSA/SSB levels confirmed her diagnosis of primary Sjögren's syndrome (PSS). PSS has a wide spectrum of renal involvement and should be a differential diagnosis when investigating interstitial nephritis and electrolyte abnormalities, particularly in patients with coexisting autoimmune conditions.

[The preparation, structure evaluation and preliminary application of biomimetic biphasic calcium phosphate scaffold].

OBJECTIVE: To fabricate biomimetic biphasic calcium phosphate BCP ceramic scaffolds using three-dimensional (3D) gel-lamination technology and evaluated their structure with 3D parameters and related method. METHODS: Series two-dimensional images of femoral head's specimen of dogs were obtained by micro-computed tomography (Micro-CT). According to these images, porous biomimetic biphasic calcium phosphate (BCP) ceramic scaffolds with oriented trabecular structure were fabricated by three-dimensional (3D) gel-lamination technology. And then, the three-dimensional structure of the scaffolds were reconstructed by computer according to Micro-CT images of these scaffolds and evaluated by three-dimensional parameters. These parameters included bone volume fraction (BVF, BV/TV), bone surface/bone volume (BS/BV) ratio, trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular spacing (Tb.Sp) and structure model index (SMI). The biomechanical properties and biocompatibility of these scaffolds were also evaluated in the study. Six scaffolds, which were combined with BMCs (bone mesenchymal cells, BMCs), were planted into the bone defect of six dogs' femoral head respectively. RESULTS: There was no significant difference between trabecular samples and BCP scaffolds in BV/TV, Tb.Th, Tb.N, and Tb.Pf (P > 0.05). The trabecular system of the scaffold, which had some orientation, represented plate-like model. With a micro-porous porosity of 62%, the average compressive modulus and ultimate strength along the axis of the scaffolds reached (464.0 +/- 36.0) MPa and (5.6 +/- 0.8) MPa respectively. The results of animal test indicated that the trabeculae of these scaffolds were covered by a layer of new bone after 10 weeks of operation. CONCLUSION: Porous BCP scaffolds have been produced with oriented microarchitectural features designed to facilitate vascular invasion and cellular attachment and with initial mechanical properties comparable to those of trabecular bone.

Cauda equina-derived extracellular matrix for fabrication of nanostructured hybrid scaffolds applied to neural tissue engineering.

Extracellular matrix (ECM) components have become important candidate materials for use as neural scaffolds for neural tissue engineering. In the current study, we prepared cauda equina-derived ECM materials for the production of scaffolds. Natural porcine cauda equina was decellularized using Triton X-100 and sodium deoxycholate, shattered physically, and made into a suspension by differential centrifugation. The decellularization procedure resulted in the removal of >94% of the nuclear material and preserved the extracellular collagen and sulfated glycosaminoglycan. Immunofluorescent staining confirmed the presence of collagen type I, laminin, and fibronectin in the ECM. The cauda equine-derived ECM was blended with poly(l-lactide-co-glycolide) (PLGA) to fabricate nanostructured scaffolds using electrospinning. The incorporation of the ECM increased the hydrophilicity of the scaffolds. Fourier transform infrared spectroscopy and multiphoton-induced autofluorescence images showed the presence of the ECM in the scaffolds. ECM/PLGA scaffolds were beneficial for the survival of Schwann cells compared with scaffolds consisting of PLGA alone, and the aligned fibers could regulate cell morphologic features by modulating cellular orientation. Axons in the dorsal root ganglia explants extended to a greater extent along ECM/PLGA compared with PLGA-alone fibers. The cauda equina ECM might be a promising material for forming scaffolds for use in neural tissue engineering.

Biological characteristics of cell lines of human dental alveolus.

OBJECTIVE: To investigate the biological characteristics of cell lines of healthy and diseased human dental alveoli. METHODS: Primary cell lines from either healthy or diseased human dental alveoli were obtained. Two cell lines, H-258 and H-171 derived from healthy and diseased human tissues respectively, were selected for morphological study and research on their growth and aging, using cell counting, and histochemical and immunohistochemical staining. RESULTS: Primary cell lines were successfully established from innormal dental alveoli. After freezing and thawing for three times, cell growth was continued and no morphological alterations were observed. The doubling time was 53.4 hours and mean division index (MDI) was 4 per thousand. Cells were kept normal after twenty generations with no obvious reduction of doubling time and MDI. Of twenty-six primary cell lines derived from healthy human dental alveoli, only three cell lines achieved generation. After freezing and thawing for twice, cultured cells were still alive at a decreased growth speed, with doubling time of 85.9 hours and MDI of 3 per thousand. Both cell lines, H-171 and H-258, shared the characteristics of osteoblast. CONCLUSIONS: Primary cell lines of diseased human dental alveoli show greater growth potential. All cell lines of dental alveoli share characteristics of osteoblast. The technique we developed may be put into practice for the treatment of abnormal dental alveoli.

[Influence of aligned electrospinning poly (propylene carbonate) on axonal growth of dorsal root ganglion in vitro].

OBJECTIVE: Poly (propylene carbonate) (PPC), a newly reported polymer, has good biodegradability and biocompatibility. To explore the feasibility of using electrospinning PPC materials in nerve tissue engineering, and to observe the effect of aligned and random PPC materials on axonal growth of rat dorsal root ganglions (DRGs) in vitro. METHODS: Either aligned or randomly oriented sub-micron scale polymeric fiber was prepared with an electrospinning process. DRGs were harvested from 3 newborn Sprague-Dawley rats (female or male, weighing 4-6 g), and were incubated into 12-pore plate containing either aligned (the experimental group, n=6) or randomly oriented sub-micron scale polymeric fiber (the control group, n=6). The DRGs growth was observed with an inverted microscope; at 7 days immunofluorescent staining and scanning electronic microscope (SEM) observation were performed to quantify the extent of neurite growth and Schwann cells (SCs) migration. RESULTS: Either aligned or random fibers were fabricated by an electrospinning process. The diameter of the individual fiber ranged between 800 nm and 1200 nm. In aligned PPC material, 90% fibers arranged in long axis direction, but the fibers in random PPC material arranged in all directions. The DRGs grew well in 2 PPC materials. On the aligned fiber film, the majority of neurite growth and SCs migration from the DRGs extended unidirectionally, parallel to the aligned fibers; however, neurite growth and SCs migration on the random fiber films oriented randomly. The extents of neurite growth were (2 684.7 +/- 994.8) microm on the aligned fiber film and (504.7 +/- 52.8) microm on the random fiber films, showing significant difference (t = -5.360, P = 0.000). The distances of SCs migration were (2 770.6 +/- 978.4) microm on the aligned fiber film and (610.2 +/- 56.3) microm on the random fiber films, showing significant difference (t = -5.400, P = 0.000). The extent of neurite growth was fewer than the distances of SCs migration in 2 groups. CONCLUSION: The orientation structure of sub-micron scale fibers determines the orientation and extent of DRGs neurite growth and SCs migration. Aligned electrospinning PPC fiber is proved to be a promising biomaterial for nerve regeneration.

[Extraction techniques and biocompatibility evaluations of naturally derived nerve extracellular matrix].

OBJECTIVE: Native extracellular matrix (ECM) is comprised of a complex network of structural and regulatory proteins that are arrayed into a tissue-specific, biomechanically optimal, fibrous matrix. The multifunctional nature of the native ECM will need to be considered in the design and fabrication of tissue engineering scaffolds. To investigate the extraction techniques of naturally derived nerve ECM and the feasibility of nerve tissue engineering scaffold. METHODS: Ten fresh canine sciatic nerves were harvested; nerve ECM material was prepared by hypotonic freeze-thawing, mechanical grinding, and differential centrifugation. The ECM was observed by scanning electron microscope. Immunofluorescence staining was performed to detect specific ECM proteins including collagen type I, laminin, and fibronectin. Total collagen and glycosaminoglycan (GAG) contents were assessed using biochemical assays. The degree of decellularization was evaluated with staining for nuclei using Hoechst33258. The dorsal root ganglion and Schwann cells of rats were respectively seeded onto nerve tissue-specific ECM films. The biocompatibility was observed by specific antibodies for cell markers. RESULTS: Scanning electron microscope analysis revealed that nerve-derived ECM consisted of a nanofibrous structure, which diameter was 30-130 nm. Immunofluorescence staining confirmed that the nerve-derived ECM was made up of collagen type I, laminin, and fibronectin. The histological staining showed that the staining results of sirius red, Safranin O, and toluidine blue were positive. Hoechst33258 staining showed no DNA within the decellularized ECM. Those ECM films had good biocompatibility for dorsal root ganglion and Schwann cells. The contents of total collagen and GAG in the nerve-derived ECM were (114.88 +/- 13.33) microg/mg and (17.52 +/- 2.34) microg/mg, showing significant difference in the content of total collagen (P < 0.01) and no significant difference in the content of GAG (P > 0.05) when compared with the contents of normal nerve tissue [(54.07 +/- 5.06) microg/mg and (25.25 +/- 1.56) microg/mg)]. The results of immunofluorescence staining were positive for neurofilament 200 after 7 days and for S100 after 2 days. CONCLUSION: Nerve-derived ECM is rich in collagen type I, laminin, and fibronectin and has good biocompatibility, so it can be used as a nerve tissue engineering scaffold.

[Fabrication of a novel cartilage acellular matrix scaffold for cartilage tissue engineering].

OBJECTIVE: To develop a novel cartilage acellular matrix (CACM) scaffold and to investigate its performance for cartilage tissue engineering. METHODS: Human cartilage microfilaments about 100 nm-5 microm were prepared after pulverization and gradient centrifugation and made into 3% suspension after acellularization treatment. After placing the suspension into moulds, 3-D porous CACM scaffolds were fabricated using a simple freeze-drying method. The scaffolds were cross-linked by exposure to ultraviolet radiation and immersion in a carbodiimide solution 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysucinimide. The scaffolds were investigated by histological staining, SEM observation and porosity measurement, water absorptiofl rate analysis. MTT test was also done to assess cytotoxicity of the scaffolds. After induced by conditioned medium including TGF-beta1, canine BMSCs were seeded into the scaffold. Cell proliferation and differentiation were analyzed using inverted microscope and SEM. RESULTS: The histological staining showed that there are no chondrocyte fragments in the scaffolds and that toluidine blue, safranin O and anti-collagen II immunohistochemistry staining were positive. The novel 3-D porous CACM scaffold had good pore interconnectivity with pore diameter (155 +/- 34) microm, 91.3% +/- 2.0% porosity and 2451% +/- 155% water absorption rate. The intrinsic cytotoxicity assessment of novel scaffolds using MTT test showed that the scaffolds had no cytotoxic effect on BMSCs. Inverted microscope showed that most of the cells attached to the scaffold. SEM micrographs indicated that cells covered the scaffolds uniformly and majority of the cells showed the round or elliptic morphology with much matrix secretion. CONCLUSION: The 3-D porous CACM scaffold reserved most of extracellular matrix after thoroughly decellularization, has good pore diameter and porosity, non-toxicity and good biocompatibility, which make it a suitable candidate as an alternative cell-carrier for cartilage tissue engineering.