The current perspectives of dromedary camel stem cells research

Saadeldin, Islam M.; Abdel-Aziz Swelum, Ayman; Alzahrani, Faisal A.; Alowaimer, Abdullah N.

Nanobodies are unique compounds secreted by members of the camelids family [19] . According to Muyldermans et al., heavy chainonly antibodies (HCAbs) that circulate in the blood of camels are different from the antibodies produced by other species [20] . These antibodies lack the light chains and are composed of a heavy-chain homodimer. They are termed as variable domain of heavy chain of HCAb (VHH) or nanobody and have various therapeutic advantages. Nanobodies are single domain antibodies derived from heavy chainonly antibodies (HCAbs) produced naturally by camelids [21] . They are considered a new generation of active proteins with unique properties. Nanobodies show excellent tissue distribution, high temperature and pH stability, are easy to produce with recombinant technology and can readily be converted into different formats such as Fc-fusion proteins or heterodimers. Moreover, nanobodies have the unique ability to bind molecular clefts, such as the active site of enzymes, thereby interfering with the function of the target protein [22] . Over the last decade, numerous nanobodies have been developed against proteins involved in inflammation, with the aim to modulate their immune functions [23] [24] [25] . Recently, nanobodies have emerged as potential candidates for targeting cancer. Owing to their very small size, they are able to penetrate the typically inaccessible parts of the solid tumors with low immunogenicity [26] . Nanobodies are also considered as a significant tool in various therapeutic disciplines due to their unique ability to bind or attach to other proteins and nanoparticles by using noncomplex chemical treatments. Furthermore, cell permeable nanobodies have been recently discovered that could permit the co-transport of therapeutically relevant proteins into target cells [27] . This technology constitutes a major step in the labelling, delivery and targeted manipulation of intracellular protein antigens. Ultimately, this approach could open the door towards targeting the intracytoplasmic pathways of living cells and the expansion of immunotherapies to intracellular antigen targets.