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Tissue engineering is based on three main factors including scaffolds, cells and growth factors. Natural scaffolds derived from decellularized tissues and organs have been successfully used in tissue engineering. Decellularization studies have shown that natural scaffolds which maintaine their main structure and properties could be a suitable tool for studying cellular behaviors and preparation of such scaffolds is an important part of future research in biology that may have extensive applications in regenerative medicine and tissue engineering. Blastema tissue which is produced after injuries in some organisms has embryonic cell characteristics, and can be a suitable model for evaluation of cell behaviors in various tissues. In this review, the process of decellularization, process involved in preparation of 3D scaffolds derived from extracellular matrix of various tissues including cartilage, bone, gingiva, aorta and bladder, and assessment of their interactions with blastema tissue under in vitro conditions are discussed.

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Background and Objective: Compression or sciatic axotomy induces neuronal death in spinal cord alpha motor neuron. This study was carried out to determine the effect of Nigella sativa seed alcoholic extract on spinal motor neuron density in anterior horn after sciatic nerve compression in rat. Materials and Methods: In this experimental study 24 wistar rats were divided into four groups A: control, B: compression, C: compression+treatment with 75 mg/kg alcoholic extract, D: compression+treatment with 50 mg/kg alcoholic extract. In control group muscle was exposed without any injury to sciatic nerve. In compression and treatment group, the right leg sciatic nerve compressed for 60 sec. After four weeks of post operation, L2-L4 and S1, S2 and S3 segments of spinal cord were sampled, processed, serially sectioned and stained with toluidine blue. The number of alpha motor neurons was counted using dissector method. Results: Neuronal density in compression group (650±32) significantly decreased in comparison with control group (1803±24). Neuronal density in C treated group (1581±47) and D treated group (1543±49) significantly increased compare to compression group (P<0.001). Conclusion: Alcoholic extract of Nigella sativa seed increased the density of alpha motor neurons in spinal cord after sciatic nerve compression in rats.

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Background and Objective: Rheumatoid arthritis is an autoimmune-inflammatory disease with possible joint destruction and disability. Persica plant, seems contain anti-inflammatory capabilities. This study was done to determine the effect of hydroalcoholic extract of Ferula persica resin on induced rheumatoid arthritis by Freund's complete adjuvant in rat.
Methods: In this experimental study, 36 male Wistar rats (200-250 g) and 8 weeks old were randomly allocated in 6 groups including normal group, positive control, negative control, and groups treated with the hydroalcoholic extract of persica resin with 25, 50 and 75 mg/kg/bw doses. The resin of persica was extracted by Maceration method. On the first day, inflammation was induced with injection of 0.2 ml of Freund's complete adjuvant into the right knee joint of rats and from the fifteenth day hydroalcoholic extract was injected intraperitoneally and daily for 15 days. On the 30^th day, blood samples were taken from hearts for rheumatoid factor measurement. Histological slides were prepared from knee joint.
Results: The level of RF in the three treatment groups was significantly reduced compared to the negative control group (p<0.05). Destruction of cartilage were observed in treated group with dose of 25 mg/kg/bw in comparision with positive control group, treated group with 50 and 75 mg/kg/bw doses. Also in the negative control group, synovial hyperplasia, pannus and the destruction of cartilage were observed.
Conclusion: It seems that hydroalcoholic extract of Ferula persica resin can causes dose dependent reduction of inflammation and destruction of cartilage result from induced rheumatoid arthritis in the rats.

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Background and Objective: Multiple Sclerosis (MS) is a neurologic necrotic and chronic illness that causes by demyelination in CNS. One of the common clinical symptoms in MS is cognitive disorders. The most common cognitive defects in patients with MS are reduction of memory and information processing rate hippocampus functions in brain are memory and learning. This study was done to determine the function mechanism of memory discover by study on hippocampus. Nowadays tendency of herbal therapy is increased because of drug's side effects. This study's purpose that is from experimental typ effect of compaind extract of Portulaca olerace, Urtica dioica and Boswellia serrata on memory and number of neurons in CA1 area of hippocampus in induced multiple sclerosis rats.
Methods: In this experimental study 30 male adult rats were randomly allocated into control group, sham group (salin injection), (MS + salin) group, (MS + mixture extract, dose of 200 mg/kg), (MS + mixture extract, dose of 400 mg/kg). MS model was induced by intra hippocampal injection a single dose of ethidium bromide (0.01% ethidium bromide sulotion in 0.9% salin) and in 3 microlitre volume with 1 microlitre in minute rate intraperitoneally. Compaind extract of Portulaca olerace, Urtica dioica and Boswellia serrata were injected as the treatment for 21 days. The shuttle box test was used for evaluation of memory. Dissector method was used for neural density in CA1 of hippocampus. Histopathology method was used for evaluation of the alteration of cells.
Results: Neural density in MS induced group was singnificantly reduced in comparison with control and sham groups (P<0.05). Neural density was singnificantly increased in treatment groups in comparison with MS induced group (P<0.05). Histological results showed that induction of MS caused the disrution of neuron cells in compare to controls, but intraperitonal injection of compaind extract cause neurogenesis in tertment groups. Memory in MS induced group was singnificantly reduced in comparison with control and sham groups (P<0.05), but memory was singnificantly increased in treatment groups in comparison with MS induced group (P<0.05).
Conclusion: Compaind extract of Portulaca olerace, Urtica dioica and Boswellia serrata with dosages of 200 and 400 mg/kg/bw due to neurogenesis and amilioration can effective in memory recovery and neural necrosis in MS disease.