The various embodiments herein relate to an injectable matrix used for regeneration, reconstruction, repair or replacement of organ or tissue. The injectable matrix consists of a synthetic and natural polymer, a stem cell niche and nanoparticles in the form of cups filled with growth factor and physiologic agent. The embodiments herein also provide a method for regeneration, reconstruction, repair or replacement of organ or tissue. In the method, an injectable matrix is injected to create three dimensional matrix system or network in an area of the desired tissue or organ, migration of blood circulatory stem cells or tissue-specific progenitor cells occur to the injected area of the tissue or organ. The growth factors and physiological agent present in the nanocups are released. The stem cells proliferate and differentiate to form the desired organ or tissue.