Tooth loss or absence is a common condition that can be caused by various pathological circumstances. The replacement of the missing tooth is important for medical and aesthetic reasons. Recently, scientists focus on tooth tissue engineering, as a potential treatment, beyond the existing prosthetic methods. Tooth engineering is a promising new therapeutic approach that seeks to replace the missing tooth with a bioengineered one or to restore the damaged dental tissue. Its main tool is the stem cells that are seeded on the surface of biomaterials (scaffolds), in order to create a biocomplex. Several populations of mesenchymal stem cells are found in the tooth. These different cell types are categorized according to their location in the tooth and they demonstrate slightly different features. It appears that the dental stem cells isolated from the dental pulp and the periodontal ligament are the most powerful cells for tooth engineering. Additional research needs to be performed in order to address the problem of finding a suitable source of epithelial stem cells, which are important for the regeneration of the enamel. Nevertheless, the results of the existing studies are encouraging and strongly support the belief that tooth engineering can offer hope to people suffering from dental problems or tooth loss.

The availability of the human genome sequence allowed us to identify a human complement-related, C1r-like protease gene (c1r-LP) located 2 kb centromeric of the C1r gene (c1r). Compared with c1r, c1r-LP carries a large deletion corresponding to exons 4-8 of c1r. The open reading frame of the C1r-LP cDNA predicts a 50 kDa modular protein displaying 52% amino acid residue identity with the corresponding regions of C1r and 75% identity with a previously described murine C1r-LP. The serine protease domain of C1r-LP, despite an overall similarity with the AGY group of complement serine proteases, has certain structural features characteristic of C2 and factor B, thus raising interesting evolutionary questions. Northern blotting demonstrated the expression of C1r-LP mRNA mainly in the liver and ELISA demonstrated the presence of the protein in human serum at a concentration of 5.5+/-0.9 microg/ml. Immunoprecipitation experiments failed to demonstrate an association of C1r-LP with the C1 complex in serum. Recombinant C1r-LP exhibits esterolytic activity against peptide thioesters with arginine at the P1 position, but its catalytic efficiency (kcat/K(m)) is lower than that of C1r and C1s. The enzymic activity of C1r-LP is inhibited by di-isopropyl fluorophosphate and also by C1 inhibitor, which forms stable complexes with the protease. Most importantly, C1r-LP also expresses proteolytic activity, cleaving pro-C1s into two fragments of sizes identical with those of the two chains of active C1s. Thus C1r-LP may provide a novel means for the formation of the classical pathway C3/C5 convertase.

Poland syndrome is a rare congenital anomaly in which affected persons are born with missing or underdeveloped muscles on one side of the body. In this case study we present the case of a 28-year-old male with absence of all middle phalanges of the right hand and other rare anomalies, who underwent reconstruction with a new method that combines a mixture of adipose-derived mesenchymal stem cells and fat transfer. The patient’s restoration of the pectoralis area was aesthetically successful with no complications and remained unchanged even after 3.5 years. The proposed method represents an interesting reconstructive approach for treating Poland’s syndrome deformities.

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