An implant system for implantation into or between vertebra of a subject's spine, wherein said implant system comprises: a first support element (11, 12, 221), one or a plurality of additional support elements (11, 12, 222, 223, 224, 225), which respectively defines a second to n-th support element (222, 223, 224, 225); a limiting member disposable around the first support element (11, 12, 221) or the one or a plurality of additional support elements (11, 12, 222, 223, 224, 225); and a guiding member configured to pass through the center of the hollow nestable structure of the first support element (11, 12, 221) or the one or a plurality of additional support elements (11, 12, 222, 223, 224, 225); wherein the first support element (11, 12, 221) or the one or a plurality of additional support elements (11, 12, 222, 223, 224, 225) is a hollow nestable structure having expandable elasticity, so as to change from a contracted configuration to preset dimensions of a distended configuration, and the first support element (11, 12, 221) or the one or a plurality of additional support elements (11, 12, 222, 223, 224, 225) is configured for being elastically self-expandable into its distended configuration; wherein, in use, the first support element (11, 12, 221) or the one or a plurality of additional support elements (11, 12, 222, 223, 224, 225) is kept in the contracted configuration by the limiting member before implantation into the vertebra or between the vertebrae, and when the contracted support element is properly positioned into or between the vertebrae through the guidance along the guiding member, the limiting member is removed and the first support element (11, 12, 221) or the one or a plurality of additional support elements (11, 12, 222, 223, 224, 225) expands elastically and automatically into its distended configuration characterized in that the n-th support element (222, 223, 224, 225) being slightly smaller in diameter than the (n-1)-th support element (221, 222, 223, 224) and configured to tightly contact an inner wall of the (n-1)-th support element (221, 222, 223, 224) after elastic expansion, so that the distended configurations of the second to n-th support elements (222, 223, 224, 225) are sequentially nestable into the distended configurations of the first support element. a first support element (11, 12, 221), one or a plurality of additional support elements (11, 12, 222, 223, 224, 225), which respectively defines a second to n-th support element (222, 223, 224, 225); a limiting member disposable around the first support element (11, 12, 221) or the one or a plurality of additional support elements (11, 12, 222, 223, 224, 225); and a guiding member configured to pass through the center of the hollow nestable structure of the first support element (11, 12, 221) or the one or a plurality of additional support elements (11, 12, 222, 223, 224, 225); wherein the first support element (11, 12, 221) or the one or a plurality of additional support elements (11, 12, 222, 223, 224, 225) is a hollow nestable structure having expandable elasticity, so as to change from a contracted configuration to preset dimensions of a distended configuration, and the first support element (11, 12, 221) or the one or a plurality of additional support elements (11, 12, 222, 223, 224, 225) is configured for being elastically self-expandable into its distended configuration; wherein, in use, the first support element (11, 12, 221) or the one or a plurality of additional support elements (11, 12, 222, 223, 224, 225) is kept in the contracted configuration by the limiting member before implantation into the vertebra or between the vertebrae, and when the contracted support element is properly positioned into or between the vertebrae through the guidance along the guiding member, the limiting member is removed and the first support element (11, 12, 221) or the one or a plurality of additional support elements (11, 12, 222, 223, 224, 225) expands elastically and automatically into its distended configuration characterized in that the n-th support element (222, 223, 224, 225) being slightly smaller in diameter than the (n-1)-th support element (221, 222, 223, 224) and configured to tightly contact an inner wall of the (n-1)-th support element (221, 222, 223, 224) after elastic expansion, so that the distended configurations of the second to n-th support elements (222, 223, 224, 225) are sequentially nestable into the distended configurations of the first support element.